We recently started playing a game of Dungeons and Dragons with several of our friends. The issue, of course, is that our DM seems to roll crits (critical hit: when you roll a 20 on an attack, it does double damage) way more often than the rest of us do. Needless to say, this has ended with us unconscious an unreasonable number of times.

There has to be a better way, no? We decided that the best gift to get for our DM for Christmas this year is a special "lucky" die, although the luck is for us rather than for him. This special die has 20 faces like a regular d20, but the numbers on it only go 1-10. Twice.

Step 1: Designing the Die

You'll need to download and install the newest version of OpenSCAD, which has support for text.

Once you've installed OpenSCAD:

open it and load the attached SCAD file;
press F6 to render;
export as STL (File -> Export -> Export as STL).

Now you have a 3D model of the Anti-Crit d20 in STL format.

From here, you have two main options:

If you have access to a 3D printer, consult the manual or online documentation for instructions on converting STLs to gcode and printing.
If not, upload the STL to Shapeways and pay them to print it. (Yes, this costs money - but it also means you have a wider range of materials to choose from!

The SCAD file is commented - if you're curious about the mathematics of crafting a d20, or if you want to tweak it to create a normal d20, read the source! (We're also happy to explain anything in there, so please ask questions!)

gmd20.scad
Download

Step 2: Fabricating the Die

The process of 3D printing is reasonably straightforward these days, so just start by 3D printing the die. Make sure you set the print to "solid", as otherwise you will end up with a weighted die (and that would just be unfair).

When the die comes out, start by taking a fine-tip permanent marker and filling in the numbers. This will make them pop better later.

Then, it's time for colors! We used nail polish to color our print: by blobbing a bunch on the surface, then waiting for it to dry, we got some nice color settled in the crevices of the die's numbers. We chose red, but any color of nail polish is obviously ok.

For the next part, make sure to wear breathing protection. Inhaling plastic dust is not good for you! Once the nail polish has dried, use a very fine sanding block or paper to rub off the excess paint and smooth the 3D printed ridges. Be careful that you hold the die very straight as you do this: you might end up with weird-shaped faces, or faces at weird angles if you're not careful. You can go back and round your corners a bit more when you're happy with the way the paint looks.

Since I still had some paint left on my die's faces, I got some acetone and a Q-tip to finish the die off. This gave everything a nice smooth finish.

Lastly, I sprayed with a bit of glitter spray, just for fun.

Step 3: Now, You Die!

There are certainly more subtle ways of making a "DM die"; for example, he might never even notice if we made a die where only the 20 was replaced by a 1. The nice thing about this die, though, is that it's actually a functional d10 (another common type of die used for tabletop games) that is in the guise of a d20. Though it's a joke, it might actually be useful someday.