Schocken Dice - Master and Mold

Hey,
I recently got into epoxy casting and dice making. This was my first project working with epoxy and creating my own molds.
For this project, you’ll need to print the master dice, create a silicone negative mold, and then cast the final dice in epoxy resin.

Using this process, you can essentially replicate almost any object, as long as it has at least one flat side. I’ve included detailed instructions below, along with some of the lessons I learned during the process.
You can also replace the master dice with any other dice or object you’d like to reproduce.

These dice are for a game called “Schocken.” I recently moved, and it’s a very popular local game here. I also designed and modeled the matching accessories (“Schockgesteck”) needed for the game. I’ll upload them shortly as a separate model.

Safety Precautions

This project uses Epoxy. I’m usually pretty lax when it comes to safety, but epoxy is some nasty stuff. It can cause serious long term harm. I strongly suggest working outside or in a well ventilated room and buying a suitable half mask from a reputable brand (from what I’ve read online cheap Chinese clones on Amazon are often not sealing properly). They’re not that expensive and come in handy for many other projects (painting, sanding, …).

Even after demolding, the epoxy still emits fumes until it’s fully cured. I usually store the parts indoors in a sealed container for a few days.

3D Files and Bill of Materials

A small overview of what you need for the project. In total, it should cost you around €20–30 to get it started.

Dice:

• The dice.stl (PLA)

• Two-component epoxy for pouring

• A set of sandpapers for post processing. Mine range from coarse (300 grit) to very fine (10,000 grit).

• Some grease / Vaseline / etc. that works as mold release. I’m using PTFE lube I have on hand for lubricating my printer’s lead screw.

• Acrylic paint for inking the numbers on the dice

• (Optional) Some Q-tips for spreading the mold release

• (Optional) Mica powder for non-transparent coloring

• (Optional) Alcohol ink for transparent colors

Tip: I bought a cheap epoxy set on Amazon that comes with many of the needed parts, plus additional items like mixing cups, stirring sticks, ...

Mold Housing:

• The dice_mold_part_a.stl and dice_mold_part_b.stl (PLA)

• Two-component silicone for mold making

1x3 Box

• Files from the 1x3 Box Folder:

  • 1x3_lid.stl (PLA)

  • 1x3_bottom.stl (PLA)

  • 1x3_inset.stl (TPU)

• (Optional) 4x Magnets (6mm Diameter, 1.5mm height)

4x4 Box

• Files from the 4x3 Box Folder:

  • 4x3_lid.stl (PLA)

  • 4x3_bottom.stl (PLA)

  • 4x3_inset.stl (TPU)

• (Optional) 8x Magnets (4mm diameter, 1.5mm height) 

Cad Folder:

Step files for remixing and my FreeCad project file.

1. Printing and Making the Dice

1.1 Print and Post Processing the Dice:

Print the dice with the highest quality setting your printer can handle.
If you have access to a resin printer, that’s definitely the best option. I'm using a standard FDM printer.
These are my settings, but use whats best on your printer:

• 0.4mm nozzle

• 0.1mm layer height

• 20% infill

• No support

• Ironing enabled
  

Print the dice with the “Schock” side up (6 on the built plate).
If you have a smooth PEI sheet, definitely use it to reduce sanding on the bottom face.
Ironing will reduce the amount of post processing on the top face and it'll also make it easier too paint the text evenly.

After printing, it’s time for post-processing. Work your way up through the grits of your sandpapers until the dice are as smooth as possible. I usually do wet sanding.
Use a very flat surface like glass to sand on, this will ensure a flat surface. I am using an old unused glass build plate.
A very clean master can save you a lot of time when making the final epoxy dice. Every minute you spend cleaning up your master is a minute less you’ll have to spend on each finished dice.

Left picture is directly after printing. Right picture after sanding from 300-10000 grid.

1.2 Making the Mold Housing

Print out the parts from the Mold Housing folder, or use any other mold jousing files you find online. Print settings don’t really matter here. You can scale the model up if you want a thicker mold.

The following instructions are for making cap molds. There are also plenty of great video tutorials out there  if you want to follow along. One I can recommend is:
Making Dice Molds Using PVC Pipe by Rybonator

Making the bottom mold:

1. Stick the dice down with tape. I am using painters tape here. Put the face you care about the least facing down. In general the top face will look the best and face facing down the worst.

2. Place the mold pieces around the dice in the center. The alignment pins should be  facing down (like in  the picture).

3. Hot-glue the mold pieces in place. Make sure every gap is sealed with hot-glue to prevent silicone from leaking. Be generous here fixing gaps while the silicone is leaking is very messy.

4. Mix the silicone according to the instructions on your bottle. You’ll need around 40 g of silicone (unless you scaled the models).

5. Slowly pour the silicone into the mold to avoid trapping large air pockets. Let the silicone cure. If you have access to a pressure pot, put it inside with ~40psi

6. After curing, there may be some flashing on top of the dice that needs to be trimmed with an X-Acto knife. You can also trim flashing along the sides of the mold if you like. Make sure to not scratch the dice master with the knife, this will lead to imperfections later

(Left and middle) show how the dice and mold housing should be oriented and hot-glued. (Right) shows the finished bottom half.

Making the cap:

1. Apply some mold release around the dice. Make sure you cover all of the silicone, especially the alignment holes. Try not to get any on the dice itself. This can cause imperfections. If you get some on the dice, just use a fresh Q-tip to clean it..

2. Flip the mold housing parts around, so that the  alignment pins face upwards now. Put them back around the mold and hot-glue everything tightly again.

3. Mix about 20 g of silicone and pour it slowly into the housing.

4. After curing, remove the 3D-printed mold and carefully peel away the cap from the bottom part.

5. Remove the 3D-printed dice. You can usually just push the mold from the bottom with your thumb, and the dice will pop out.

6. Congratulations! You’ve made yourself a dice mold! you made yourself a dice mold.

1st picture: Green areas show where to apply mold release.
2nd & 3rd pictures: Flipped mold housing with the hot-glued parts.
4th picture: Finished cap mold.

1.3 Pouring the Epoxy Dice

I won’t go into detail here, but there are lots of different techniques and tutorials online for making dice from a cap mold. Just have fun with it and experiment with different colors and techniques. I recommend starting simple with a single colored dice, and once you’re successful get more creative.

You can use mica powder to create solid-colored dice or alcohol ink for transparent dice.

What is a Pressure Pot and Do You need One?

A pressure pot is a vessel you can put pressure in. This will cause air bubbles trapped inside the epoxy to shrink and being close to invisible.
The air bubbles get introduces while mixing and pouring and will cause imperfections. It's close to impossible to completely avoid creating any bubbles.
It's quite an investment to get a pressure pot, but it definitely comes in handy when you work with epoxy more often.

Without a pressure pot, you can still create really nice-looking dice, they just won’t be perfect. In the pictures below the left dice was cured inside a pressure pot, and the right one without it. I used transparent dice here, with  solid colored dice the bubbles are a lot less noticeable.

Here are some tips to reduce the number of bubbles if you don't have access to a pressure pot:

• Warm your epoxy bottles in warm water beforehand. This makes the epoxy less viscous and therefore reduces the amount of bubbles (Be careful, this also shortens your working time)

• Mix very slowly, moving in one direction as much as possible to introduce as little air as you can.
  It's also helps to use a tall and thin container so there is as little surface area of the epoxy with the air.

• Place your container of mixed epoxy in warm water and wait until bubbles rise to the surface. Make sure no water gets into the epoxy. This can/will ruin the curing process. You can also stir a little bit more while the epoxy is in the water bath to try to move the bubbles to the surface.

• Use a lighter to remove surface-level bubbles.

• When pouring the dice, go as slowly as possible.

Tip:  If you’re using a pressure pot, you’ll also need a way to pressurize it. Usually you would use an air compressor. Since I live in an apartment, a loud compressor wasn’t an option.
There is an easy hack. You can convert a pressure pot to work with a regular bike pump instead. All you need is a 1/4" NPT to Schrader valve adapter.

1.4. Post processing and Inking

Depending on how smooth your master is, the amount of post-processing needed will vary.
For my dice, I usually only need to sand down the face with the 6. All the others faces are usually close to perfect.
Similar to working on the master, work your way through the finer grits of sandpaper. I usually start with 5000 grit and go up to 10,000 grit.

Once the dice are fully cured, it’s time for inking. Simply use acrylic paint and a small brush to fill in the numbers. Be generous, it doesn’t need to be perfectly precise.
After painting each face, use your thumb or a cloth towel to wipe off the excess.
Once the paint is dry, you can use some IPA to clean off any remaining paint.

2. Printing the Boxes

2.1 Print the TPU insets

Just use the TPU settings that work best for your printer.

The insets can be press-fitted into the bottom housing. They’re a pretty tight fit, so you might need to use some force to assemble them. If your printer’s tolerances aren’t great, you may need to scale up the bottom or the lid by 1–2%.

2.2 Printing the Bottom and Lid

Just print the bottom and lid files with your standard PLA settings. I used these for reference:

• 0.4mm nozzle 

• 0.2 mm layer height

• 20% infill

• No support

• Fuzzy skin enabled (make sure to check your sliced model. In some slicers fuzzy skin will be also applied to the inside walls)

• Z-seam random

Fuzzy Skin:
Fuzzy skin can cause issues in some slicers. Sometimes  the texture is also applied to the inner walls of the lid. This will screw up the fitment with the bottom part.
If that happens, use the *fuzzy_template.stl file. Import it together with the regular part and make sure both models are aligned in the exact same position.
Then enable custom print settings for the intersecting area and apply the fuzzy skin effect only there.

Adding Magnets (Optional):
The models come with holes to embed magnets mid-print. In my opinion, this gives the box a more premium feel and helps keep the lid from falling off.
If you want to add magnets, you’ll need to pause the print at specific layer heights to insert them. The exact steps may vary depending on your slicer:

• Import the model into your slicer.

• Slice the model.

• In the preview, scroll through the layers until you find the last layer where the hole for the magnets isn’t printed over. This is the layer to pause on.

• Add the pause-on-layer command (how this is done depends on your slicer).

For the 1×3 boxes, you need magnets with a 6 mm diameter and 1.5 mm height. For the 4×4 box, use 4 mm magnets with 1.5 mm height.

When the print pauses, press-fit the magnets into the holes and secure them with some superglue. Then resume the print.
Important: Make sure the polarity is correctly. You don’t want the box and lid to repel each other.