weblog.masukomi.org - 3dprinting

Remarkable Tablet Wedge

2025-03-05T00:00:00-05:00

Table of Contents

Overview

After writing a few hundred pages on my reMarkable Paper Pro I decided to stop using my stuffed monkey, trivets, and other found objects to prop up my tablet when writing. What came out was a simple object, but also one of the most satisfying things I’ve ever made, for physical, and emotional reasons. This post goes over what I did, how I did it, and why it means so much to me. If you just care about the last bit skip to “Satisfaction” at the end. If you are interested in 3D printing, read it all.

Problem Statement

Writing is just easier when the surface you’re writing on is angled towards you. Having something angled at the correct angle for your body is even better.

I want something that…

feels, and looks solid.
isn’t as large as the tablet itself
can be easily carried around the house

First Attempt

I took some measurements, did some math, and even worked through what a collapsible stand might look like.

The first version is a simple object. It only took me a few minutes to model it, but there are a couple things I’m proud of. First, I was smart enough to subtract the height of the felt pad on the bottom from the height of the wedge so as not to mess up the angle. The second thing is that my experience with 3D printing kicked in before I sent it to the printer and chose an print orientation that would avoid having any notable steps between layer lines.

It worked well enough, but there were two problems:

First: It turns out I regularly rotate my tablet as I’m writing for wrist and hand comfort. I had no idea. There’s nothing forcing the wedge to shift with the tablet. The cover is fricative, and adding a felt pad to the top would introduce enough friction to solve this problem, but it irks me on an emotional, almost physical level. It would be ugly, and I don’t like the idea of grabbing some wedge that’s felt on both sides.

Second: I find myself seriously annoyed by the wasted space of its interior. I wanted a drawer. I don’t have anything to put in that drawer, but I want it.

The color change was a happy coincidence. I ran out of the sparkly grey “metal” filament and swapped to a matte Marine Blue filament. And the contrast of shiny sparkly and matte in those two colors is amazing in real life. Alas, recreating it in v1.1 would require a lot of wasted filament because of how it has to be printed.

Second Attempt

Solving For Rotation

My unwillingness to rely on friction to solve the rotation problem meant I needed “ears” or “lips” maybe? I’m not sure what to call them. Little edges that stick up. I was considering only putting one on the left, but wise Wifey talked me out of it. The problem with having ears on both sides, is that they need to be close enough to the sides of the tablet so that they start rotating the wedge quickly, but also far enough away on the right that you can easily attach the pen to the side for storage and charging.

The ears did introduce a printing complication.

The Drawer

Requirements

must not slide out freely when carrying it around
must provide no opening for contents to fall out when carrying around
must be big enough to support pens, styluses, and other items.
must be aesthetically pleasing

Staying Shut

Initially I wanted some kind of push-to-open mechanism. I used a bunch of notebook pages working out ways of doing this with an array of magnets arranged in opposing and attracting patterns to create a spring mechanism, then a rack and pinion design. Then I practically face-palmed when I realized I’d just solved this exact problem with simple plastic spring tabs with corresponding holes in my small under-desk drawer design.

I started to iterate on that, but then realized I could do something more elegant with magnets.

Hidden inside the print are two 10mm x 2.75mm disc magnets. They’re hidden not just by virtue of being deep inside the wedge, but also because they have two layers of plastic encasing them. I did this because rare earth magnets are surprisingly fragile, and I was concerned about whacking the magnets in the drawer against these repeatedly. I wanted to cushion the blow, both because it’s impossible to get in there and replace them, and because I didn’t want the “clack” sound of two magnets hitting.

This introduces printing complications.

The drawer has another pair of magnets in the corresponding location. I considered encasing these as well, but doing so would have introduced a significant printing hurdle, and I don’t have a problem the aesthetics, especially since you rarely ever see them.

Magnets Magnets Everywhere

I have a variety of small magnets in my toolbox for projects like these. I experimented with thin rectangular ones that were 1mm thick, and a variety of small disc magnets until I found some that were wide enough to address any potential alignment issues between the magnets on the drawer and the ones in the wedge, and had the right amount of pull. 1mm thick just didn’t provide enough force, and they’re trivially easy to snap. 10mm x 4mm proved too much force. I experimented with some 6mm x 3mm but the 10mm x 2.75mm I settled on had a nice balance of surface area and pulling force.

Opening

Having a pull tab that poked out past the side wasn’t an option, nor was having something small and fiddly that you could only get your fingertip into. I wanted something easy to use that felt nice to touch when using. After some sketching, and modeling I ended up with this.

In hindsight, I can see that it’s a swanky version of the pull handle you see on most file cabinets that I’ve rotated 90°. After measuring my finger, I worked to create a curve that would guide my finger gently into the right position to remove the drawer. I intended to cover the top of this, but my gut told me that it would look cool to leave it exposed. I was not disappointed.

Leaving the top exposed also solved a printing problem.

Feel

While I wanted a flush face when closed, I also wanted rounded corners everywhere else. I hate handling unnecessarily sharp edges. So, all the inner and outer edges that wouldn’t effect the flush-fit of the face have been rounded.

This introduced the need for a little bit of math, because rounded edges of the drawer that fit into the rounded edges of the hole have to have a slightly smaller radius, and that needs to account for the way the plastic spreads as it cools. In the end the hole has a 3mm radius fillet (curve) on the bottom edges, and the corresponding edge on the drawer has a 2.2mm radius fillet.

The Printing

I had three problems to deal with.

both pieces had to be printable without supports. First: because I wanted nice smooth surfaces and supports always leave imperfections. Second: because the places where you wouldn’t see the result of using supports were places that would be incredibly difficult to cleanly remove them.
Filament expands as it settles and cools, and glue isn’t infinitely thin.
Some magnets needed to be completely encased in plastic.

No Supports

In order to encase the magnets in plastic, the wedge had to be printed on its end which meant that the upper “ear” would be hanging out into open space. Supports are almost always needed in that scenario, because you can’t just print into empty space and expect the hot filament to not fall down. But, if you can offset each layer juuuust enough you can create an achievable arch or angle. Back in the cad software I increased the radius of the inner fillet (curve) where the ears meet the top of the wedge.

The drawer didn’t need any supports because the magnet holes on the end were large enough that the top arch of the circle could support itself as it was printed, and I’d chosen to leave the finger pull open at the top.

Because of the way a standard filament printer works, it just wasn’t possible to encase the drawer’s magnets in plastic and have no supports. I decided to leave them exposed.

Expansion & Glue Issues

You can’t print a 10mm void and expect a 10mm magnet to fit. The filament will squeeze inward as it cools and create a hole that’s slightly too small. With my printer I can pretty reliably assume just under 0.2mm of spread. When I add that much to the radius of the magnet hole, I get an almost perfect fit.

In the case of the drawer I designed it to be 0.8mm smaller than the hole it was fitting into, on all dimensions. This ended up being perfect.

In order to account for the gel-like Cyanoacrylate glue (Super Glue) that would hold the magnets in place I added 0.25mm to the depth of the magnet holes, and that worked out perfectly.

Encasing Magnets In Plastic

There are three complications with embedding magnets in a print

You have to stop the printer mid-print, insert magnets without disturbing anything or getting glue anywhere it shouldn’t be, then resume the print.
I use a hardened steel nozzle, which the strong rare-earth magnets really want to stick to as it passes above or nearby.
The inserted magnets need to not interfere with the print head when it goes to lay down the next layer.

The first problem is pretty easy, but required a little prep. I added a pause in the slicer just after the layer that finished the walls of the magnet holes, set a timer for 33 minutes into the print so that I’d have a couple minutes to get ready, grabbed gloves, glue, paper towel, and a magnet insertion tool.

The tool is just a plastic wand with a magnet glued to the end of it, but it’s critically important because it guarantees that I have the magnets pointing in the correct direction, and it keeps my fingers away from the glue.

When the pause was about to happen I had gloves on, two magnets ready to be picked up with the tool, the flow pre-tested and ready to squeeze - sometimes the bottle gets clogged. When the printer paused, I picked up my tool, picked up a magnet, added a small amount of glue to the magnet, carefully inserted it, wiped away any excess glue, and repeated. Then I waited a full minute for the glue to set because CA glue cures by being exposed to air, and there is basically no air on it when it’s squeezed into the hole.

The problem with magnets not being able to interfere with the print head is the main reason I couldn’t encase the ones on the side of the drawer. Not without leaving a void around the top half of the disc which I wasn’t happy with.

Satisfaction

The end result is, in my opinion, beautiful.

That’s not what’s really satisfying for me though. The first glimpse of that feeling came when I slid in the drawer for a test fit before inserting its magnets. The fit is so perfect that the air pressure cushions it as it approaches the end of the insertion, and gives a hint of resistance as you pull. Not only that, but it stays in really well without the help of magnets.

It’s a satisfying feeling, the gentle friction as it slides, and the effects of the air pressure. It was also a reminder of how far I’ve come. With a combination of experience, and trusting my gut for aesthetics and some measurements, I was able to design something that does fits beautifully; both itself, and the tablet it was designed for. It printed beautifully. Encasing the magnets went perfectly. I love the way it feels as my finger slides into place, guided by the curve. I love the way it looks when I see my finger curled into that handle. I love the flush fit of the drawer, and the soft curves of the edges I hold on to.

Creating this simple object required a lot of experience to not only know what complications would be encountered, but to know how to address those issues. Even the simple curves of the edges are the result of years of experimentation to know what feels good, what looks good, and what constituted big enough, but not too big.

In the end, I’ve created something I’m really proud of, that has helped me see just how much I’ve learned on my journey to be a better Maker.

Want One?

I’m considering selling physical versions of this, and the models with assembly instructions, and a bill of goods for the felt bottom and magnets, for people who have 3D printers. If you’re interested drop me a line on the Fediverse (Mastodon) at @masukomi@connectified.com or via email at masukomi@masukomi.org. I’m not very good with email though. Physical ones would probably be $40 or more. The raw materials to print and ship cost ~$11 USD and that doesn’t include time spent cutting the felt foot to shape, attaching it, or having to be sitting beside my printer at the precise time it will pause so that I can insert the magnets. 😉

Postscript

You may have noticed that the new wedge is entirely Marine Blue except for the side with the drawer. I ran out of Marine Blue filament 96% into the print. I swapped it for something else while half asleep at ~4 AM when the dog asked to go pee. The color was lighter than I realized in the dim light, but it was already starting to work its way through the system when I realized this, and I was too tired to deal.

It works great in photos for showing a clear distinction between drawer and side though. So, another lesson learned for future product shoots.

What is 3D Printing Good For?

2024-02-19T00:00:00-05:00

Table of Contents

Overview

There are a lot of folks out there who are interested in 3D printing, but then they look at one of the many sites of free models like Printables and see a lot of silly tchotchkes that seem like a waste of plastic and space, or cheap things they can already buy cheaply like pen holders. Recently someone asked the following question on Reddit.

What type of people need a printer?

I’ve been sitting on the idea for 4 years to buy a 3D printer but every time I decide against it. In my mind, If I need a small part for something, I’d rather just buy a quality version of it instead of a brittle plastic one. I considered it for small tools for locksmithing but … why would I? I can just buy the real thing and have it last years. I think it’s useful for intense D&D players or cosplayers but that’s not me. And every time i research useful things to make with a printer it’s always stuff like “pen holder, mini plant holder, phone case, remote mount”. Which I have to admit are pretty lame for a $200-$500 machine and materials. Everything I read can be found at a dollar general. But they have to be popular for a reason right?

So who consistently uses a 3D printer? What do you personally use it for that isn’t just a holder for a small thing? Can you justify printing something over just buying it?

It’s a totally reasonable question, and one that I’ve answered variations of a bunch of times. This post assumes you don’t know a lot about 3D printing and are wondering if there’s any “real” value to getting one.

First though, let’s address some conceptual housekeeping so that we have a common understanding going forward.

Terminology

When people say “3D Printing” what they usually mean is “FDM” (Fused Deposit Modeling) printing. This is where you’ve got a spool of filament that is gradually extruded through a hot nozzle and builds up a print layer by layer. There are countless practical uses for this, but it’s not good at printing fine details (sub millimeter).

However, at the consumer level there’s also “Resin” printing, which uses light (laser or LCD) to strategically harden layers of goo. This is a messier process that involves dealing with some nasty chemicals but produces pieces with incredibly fine detail. This is great for things like D&D Minis.

Plastic types

short version: PLA, ABS, and TPU are 3 of the many filament types available, and I’ll be referring to them later. If you don’t care about details skip this bit.

PLA is the most common filament. It’s made from Polyactic Acid which is technically “plant based” but even when there aren’t additives it’s not something that’ll break down quickly in the environment or even in a composter.

ABS is what’s most commonly used in injection molding, but some home 3D printers can print with it too. As a rule of thumb, if you buy anything plastic it’s probably made with PLA. It’s got a lot of good properties. However, it releases some truly nasty Volatile Organic Compounds when you heat it for printing that you really shouldn’t breathe. The biggest reason to use it is that it’s got enough heat resistance to be stuck on the dash of a hot card in summer and not melt. There are better alternatives, and many aren’t as nasty.

TPU is a “rubbery” filament that can be used for gaskets or things where flexibility is important. It comes in multiple levels of… floppyness. Technically this is called the “Shore Hardness”. I don’t know why. What’s important, is that this is a very useful option for consumers The softer it is, the harder it is to print.

Resins Unfortunately this is not an area I can really speak to with authority. I know there are many available, and that it’s easy to mix pigment and sparkles into the clear resin to make something a particular color, but most folks seem to use it to print grey things that they paint afterwards.

Misconceptions

Strength

For most things you’re likely to want to print FDM prints are more than strong enough. Especially when it comes resisting compressive forces. They’re less good at resisting being pulled apart. However, we’re talking over 900 Newtons of force to rip a standard PLA (the most common filament type) print in half.

Lasting Power

3D prints last a LONG time. Despite being “plant based” the things you print with PLA are going to outlast you. It may fade in sunlight, but that’s true of most plastics. PLA is NOT good in water, but other filaments are.

Degradability

Multiple filament makers promote the fact that PLA is “Plant Based”. It would be equally accurate to say that petroleum based plastics are also “Plant Based”. Some filaments say they can be composted. Alas, this is only technically true. It would have to be an industrial composting facility which has significantly higher temperatures than your back yard, and even there it’s so problematic that they generally won’t accept them.

PHA filament from ColorFabb is the only one I’m aware of that is truly compostable, even in a home composter. However, at the time of writing (Feb, 2024) it’s pretty new, not cheap, and very few people have actually worked with it.

Filament Reusability

It’s technically possible to re-melt filament from old prints, but in practice it’s surprisingly expensive and non-trivial. I have a blog post explaining how to recycle 3D prints.

Food Safety

Even if you print with a food safe filament, FDM printed items are not food safe. The problem is that bacteria can hide between the layer lines and resist cleaning. Using a food safe filament for things like organizing your cutlery drawer is fine though, because the print is never going to come into contact with food.

Printing Minis

People who play tabletop games like D&D or Warhammer generally like to have miniatures representing their characters or troops. Your common FDM printer is not going to be good at this. They just can’t reproduce the level of fine detail you need. You need a Resin printer for this. The good news is there are some really affordable, good quality ones that can easily print most minis.

What’s it good for?

If your primary desire is to print gaming minis, a cheap resin printer from a reputable maker will pay for itself in a week. There are tons of excellent mini designers out there with very affordable models. You’ll never need to model your own. Just be careful about getting one with a big enough print plate for the things you want to print.

For everything else though…

It depends on your willingness to learn how to model things yourself. Simple shapes are easy with tools like Tinkercad, but the more you get into this the faster you’ll get frustrated with how hard it is to do anything but the simplest of shapes. Learning real CAD (Computer Aided Design) software is a fair amount of work, but it’s absolutely worth the time investment. There aren’t many good options between “beginner” and “professional”. The most popular professional tool for amateurs is Fusion 360. It has a free plan, and there are tons of video tutorials that’ll help you learn it fast.

If you’re not interested in spending time learning a professional level tool, then frankly I don’t think you should bother getting a printer. Tinkercad is fun and easy but incredibly limited and hard to do anything complicated with. Sites like Printables do have a ton of things you can download and print, but most of it is not anything you really need often enough to justify buying a printer. The big exception might be the ever-expanding Gridfinity organizational system.

Where 3D printing really shines though is not the stuff you can download and print. It’s the things you can’t buy, and sometimes the things that are unreasonably expensive to buy, or ship.

Fixing Things Manufacturers no longer value “high quality, well made” things that last a lifetime. Things are constructed as cheeply as possible, have no replacement parts available, and are rapidly abandoned by their makers. Things will wear and break in ways that shouldn’t require throwing them out and researching potential replacements.

If you know how to measure and model things you can make just about any plastic replacement part you need: replacements for worn gears, broken switches, lids, etc.. The only real restriction here is heat. If you need something that can survive the heat of a car on a hot summer day with full sun, then you’ll need some special filaments which require higher end printers and ventilation systems that aren’t easy or cheap to set up.

3D prints can also be used to make molds for poured metal parts like brass gears, or metal sculptures.

Prototyping Thinking about making a physical object for sale? Need a way to cheeply iterate on something in the real world? Maybe confirm that it fits and does what you expect before spending a lot on making a metal version? 3D printing’s great for this.

Solving Unique Problems This is where 3D printing truly shines. Once you learn how to quickly model your own things the possibilities for solving real world problems are endless. It’s hard to convey a sense of just how many things you can do, so instead I’ll give you examples of what I’ve used mine for in the following section.

How I use Mine

Non-exhaustive - and unordered - lists of things I’ve printed and hope to soon print.

Things I have printed

a custom system for managing notecards to help keep track of all my ideas

bolt covers to keep the bolts on the bottom of my desk from ripping my jeans, and pressing into my legs uncomfortably.

custom dividers and inserts for Milwaukee packout cases
things to organize my tool drawers: bit organizers, socket organizers, lots of Gridfinity things
a custom keyboard and trackpad holder to address a friend’s accessibility issues (palm rejection doesn’t work for him so laptops always think he’s mousing when he isn’t). Technically this is still in-progress.

custom mounts for my split keyboard to attach to my desk so that the right half stops “going walkabout” while I’m trying to use it.

I’ve actually made two different versions of these to attach to two different desks and at different distances. One for myself, and one for a friend.

one for my friends desk with an longer curved & angled front because his keep sliding down the front edge.

custom dice trays, with leather bottoms that attach to the sides of my wooden lap desk, and then connect together with a rubber (TPU) gasket that holds them closed like a clamshell.

a valet tray that I use in our freezer because the weird silicone ice cube tray i use to make Tea Cubes has a habit of overflowing and leaving a creeping frozen brown in the freezer… or it used to.

Currently working on an adapter for my Dremel Drill press to allow it to mount the soldering iron I use for heat-inserts
custom organizers for board games with lots of pieces and / or cards
a custom organizer for games with lots of little tiny markers or dice that suck to put into or remove from those terrible little zip-lock bags they come in.
a custom pen/pencil holder that attaches to the side of the little side-table shelf thing that sits next to my side of the couch.

a custom single index card clipboard that fits in a pocket and allows me to write a note on one anywhere.

custom switch cover to install a switch in a big gaping hole in our ambulance.

more custom switch covers
a light box for photography

A jig for evenly spacing and aligning the LED strips for that light box.

A Micro Jib (video link) for photo and video purposes.

A jig for precision cutting of steel rods for the Micro Jib

A custom hole cover to protect wires from sharp metal edges

A Paper Towel holder mount

A special flexible plastic to adjust the seal on a CPAP

coasters

new discs for my disc binder
bookmarks that attach to disk binder disks
custom tool holders

adapter to allow me to use cheaper, easier to find HEPA filters with my printer enclosure

tons of mods for my 3d printing stuff. Everyone does this though.
Tool holder wall (I went with the Honeycomb wall, might go with Multiboard if i revisit this.)
jigs for holding dice I laser etch.

jigs for holding other things.
magnet insertion tools
a fake rock with cutouts for holding a small bottle of medicine and a syringe.

A custom tool to facilitate cutting lids off of 5 gallon water bottles.

D&D Minis. These were on my last FDM printer and they were not very good.
Headphone hangers
Fixed a lamp. It fell over and the ring that held on the diffuser no longer fit. So I printed a replacement out of flexible filament.

Warning

If this post has convinced you to get a 3D printer, I must give you a warning before you do. Cheap FDM printers are, in my opinion, a pain-in-the-ass. I almost never used my first printer because it was a constant series of frustrations and poor quality prints. There are thousands and thousands of posts on reddit of people asking why their print has one of a hundred different possible problems. Getting a $200 (USD) printer dialed in to make great prints is possible, but it’s a lot of frustrating work that feels like your trying to read tea leaves.

My current recommendation (February 2024) is to get any of the printers made by Bambu Lab. The more you spend the more you’ll be able to do with it. The reason I recommend Bambu is because their printers are the closest anyone has ever come to making a printer that’s as easy to use as a Laser Printer. It’s not quite as easy yet, but it’s damn close. Getting a printer with an enclosure like their X1 Carbon (X1C) will make your life easier, because the ambient temperature has a significant impact on the quality of your prints. Unfortunately, the X1C + the multi-filament management system (don’t buy it without that) is like $1500, and then you’ll need to buy filament.

I use my X1C probably 3 times a week on average. I never print tchotchkes.

Feel free to ask me questions on Mastodon. I’m happy to help people out.

Rounding Things In Tinkercad

2023-04-16T00:00:00-04:00

Table of Contents

Overview

A Guide To Rounding Corners and Edges in Tinkercad.

Alternately, how I spent way too much time modeling a dice tray.

Rounding corners in Tinkercad is way more trouble than it ought to be. It’s not actually hard, it’s just really time consuming and requires a lot of steps. Once you wrap your head around the general approach you’ll be able to round anything.

This post will take you through the steps required to round the and edges on this simple dice tray.

Step-By-Step

High level rounding:

In most case you can simply stick a rounded thing on top of a rectangular thing and that’s it. For example, most of the walls in this are simply rectangles with half-cylinders laid lengthwise on top of them. That’s the bit you probably don’t need help with.

When you can’t simply build the shape you want, but instead need to round off an existing corner the approach is actually fairly similar. You build up the shape of the cut, cut it out of something, and then turn that something into a “hole”. For example: this image shows the sequence of things I’d do to round off one edge of a cube. I take a cylinder, which has the rounded shape I want, then cut it out of a another cube or rectilinear shape that is at least as large as the thing I want to round off. Then I convert that shape into a whole, and use it to cut off the edge of the cube.

Pro-tip. Make the thing that will be your cutting tool an even multiple of the size you’re cutting out of it. For example. The cylinder is 10mm into the cube I’m going to cut. The cube is 20mm wide. This means that when I use the resulting hole to cut into other shapes I can simply overlap them by 10mm.

The Corners

The corners are the most complicated part of this build. In order to have them curve over the edge on the top, but be flat on the bottom I needed to create a cylinder with rounded edges that were different on each end.

To build the bottom of the corner we take a torus (donut) and stick it on top of a cylinder. It’s much easier to build this upside down and then rotate it.

Note that the “Tube” slider controls the radius of the curved cylinder that makes up a torus shape. Your life will be significantly easier if you can make this a whole number. I wanted a 3mm wide wall, so I used a 1.5mm “Tube” which just made all the future placements of objects much more difficult. If I was doing it again, I’d just make the wall 4mm thick. Change the “tube” setting to be the size you want, then deal with the outer dimensions. Changing the tube radius alters the outer dimensions, so there’s no point in setting those first.

For the bottom we need to add a cylinder that fills the area from the top of each rounded side of the torus. This means we need a cylinder that is the diameter of the outer cylinder, minus the radius of your “tube” times 4. Set a ruler at the corner of the initial cylinder to help you place this inner cylinder correctly. The inner cylinder will be the height of the initial cylinder plus 1x the radius of your “tube”.

So, if we have a torus that with a 2mm tube (radius), and it sits on a cylinder that is 20mm in diameter, and 20mm high, then your inner cylinder will be 16mm in diameter and 22mm tall. To position the inner cylinder move it 2mm towards the center along the X and Y axis.

This picture shows the bottom of our corner with the pieces put together, and with the center cylinder offset. Now Shorten the outer and inner cylinders by at least the radius of your tube, and then shift them back up into position. Copy this shape, and set it aside, so that we can use it as the start of our top corner. Then group these pieces, and rotate it 180° to form a nice flat bottom with rounded edges, and drop it down so that it touches the ground.

Take the copy you set aside, and change the diameter of the inner cylinder by subtracting 4x the radius of the tube. Now it’s 12mm in diameter, and should look like it’s poking through the center of your torus. Convert that center cylinder to a hole. Now, shorten your cylinder by the radius of the torus. Then shift it up so that it’s touching your top torus, and hovering above the ground. and then combine all the pieces of the top here except for the hole. Make sure the bottom and top have different colors so that you can better see what’s happening in the next step.

Bonus points: If you want the inner curve at the bottom to be rounded too, add a half-sphere on top of your hole cylinder, combine them, and rotate it. Make sure that the bottom (the tip of the half-sphere) is the thickness of your floor away from the ground.

Combine the top and bottom pieces, then group everything. The process should look like this.

The next step is to cut away the excess and make it into a corner piece. For this I just take 3 cube holes. Each cube should be 2x the diameter of your cylinder. Arrange them so that they all intersect at the center of your cylinder, and are raised up the radius of your “tube”. Then combine all the shapes. Here’s the before and after.

Now we’ve got our corner piece.

You’re past the hardest part.

The “ears”

There are a couple ways to address this. You can take a rectangle, and attach 3 half cylinders of the appropriate size to the edges. I wasn’t so smart. I built the thing with rectangles and then cut away pieces.

Sooner or later though, you won’t be able to do this, and you’ll need to round off something as shows in the earlier sequence.

The thing worth copying here is the rounded corners. To make these you simple create a disk. This is just like creating the bottom of the corner, except that the height of the inner cylinder is 2x the “tube” radius of the torus it’s going inside. Combine those and you’ve got a disc with rounded corners. The torus you start with should have a diameter equal to the thickness of the thing you’re rounding.

Chop off a square corner from the item where the disk, then slide the disk into place, and combine the things.

Everything Else

Everything else is just a repetition of the techniques outlined above. In order to merge the floor with the corner pieces with the cylindrical bottoms, you just use two overlapping rectangles. It’s important that your floor extends to the middle of the wall. This is so that it will not extend past the apex of the curve.

You may notice that mine are not placed identically relative to each corner. The way my walls are constructed it doesn’t matter, and the resulting gaps are hidden.

A Template For The Leather

I wanted a nice fit for the leather insert. In order to make this I took the final model for the tray, and separated all the pieces. I combined everything except the floors, and then made that into a “hole”. I combined the floor pieces and then cut the hole out of them. This left weird corners. So, I grabbed the cylinder I had used to cut a vertical hole in the corner, converted it to a solid, and moved it, and a copy, into position on each corner that needed to be rounded.

Then I combined them. There was no need to make them taller. It was just easier to move around in Tinkercad if they weren’t the same height.

Now, this template is the exact dimensions of the floor. If you account for expansion of the filament during printing you’ve got a template that won’t fit into the tray because it’s micrometers too big.

This is ok for leather. I placed it on top of the leather I was going to cut, and then angled my blade at roughly a 45° angle towards the center of the piece. This gave me very thin leather at the top, and a bottom of the full thickness. The result is that when I set it into the tray the edges are a hair wider than the hole they’re going into, but they’re also very thin there. This exerts just enough pressure to hold the leather in place without any adhesive required.

The leather I’ve chosen is very soft. This is beneficial in such a small tray because it absorbs most of the impact of the dice. They stop rolling almost instantly, which is good, because they have very little space to roll in this tiny tray.

Conclusion

That’s it. I hope this helps save you from the hours it took me to figure all this out. If you find this helpful, or confusing, please drop a line to me on mastodon at @masukomi@connectified.com or drop me an email at masukomi@masukomi.org.