Carving Custom Dice

I've been casting my own dice. I've been refining my methods and I'll share what I've learned here.

I don't worry about making balanced dice, although when tested these don't do too badly with roll distribution. I mention that because some people really worry about having absolutely perfect roll distribution. That's not my goal here.

To make your own custom dice, you'll need an example die to start out with. Start with an oversized die. A large die is easier to carve, particularly getting the numbers legible. A very large die seems to take details easier. I have two blanks I work with and my chonk die has never failed to cast properly while my smaller blank has a 50/50 chance of failing the cast.

I made my blank molds a while ago, but I'll show how to make a mold later and the process is the same.

You'll Need

A large die to make blanks from.

Wax - Melted candle wax is fine but there is mold wax that's available on amazon.

Some way to melt the wax, I use an electric hot plate. A small crock pot also works well.

A fine point knife, pin, nail or wire for carving the wax.

A mold material - I'll show how to use 100% silicone caulk, but a pourable latex or silicone would be better.

Nitrile gloves.

A small paint stir stick or rubber spatula to mix and spread mold materials.

Food coloring if you're using silicone caulk for molds.

Melamine from an old shelf or a small plastic cup to make a mold in.

A utility knife or exacto knife for cutting open your mold.

Clean sand and plaster of paris in a ratio of about 50/50. You can get plaster of paris in the paint section of the hardware store.

Used steel cans are helpful for making plaster molds in.

A metal melting furnace and a crucible.

Make a box out of melamine that is just a little bigger than your blank die. It's helpful to have one or more removable sides for removing molds. You can also use a small plastic cup as long as the mold material will release from it.

Put on your nitrile gloves. Spread some silicone caulk on the inside of this box. You can use a rubber spatula or paint stir stick to do this. Cover the surface of the die in the mold material. Don't worry about using your hands to get the silicone on the die if you're wearing gloves. Insert the die into the box and make sure to fill any voids with silicone.

Allow the mold to cure in the box overnight. Once cured, peel the silicone out of the box and cut the mold in half with an exacto knife or razorblade. If you use a zigzag cut, it will ensure that the mold halves pair back up properly.

If you add a few drops of food coloring into your silicone, it will color the final mold and make it cure faster.

We'll go over the mold process again in more detail for the carved wax. The process of making the mold is the same in both cases.

Remove the die from the mold.

Find the highest corner in the mold and cut a small hole. This is where you'll pour wax into.

Reinsert the mold into your box without the die inside. Melt a small amount of wax and pour it into the mold. Tap the side of the box to make air bubbles float to the top. If you're scavenging wax off crayons or candles, some waxes shrink a lot when they cool, you may have to top off the wax in the mold as it cools. Try a few different waxes and find the one that works the best for you. Different waxes will also have varying melting temperatures.

This volume of wax usually takes 10-15 minutes to cool enough to demold. If you demold too soon, you can deform the wax and your die will not have even sides.

Starting with your wax blank die, you can draw a rough plan on the wax for what you want it to look like with a sharpie marker. Using the sharpie is helpful because design elements on the die can run into each other and cause problems if they're not planned for. Here I'm carving an octopus into the die with the head at one vertex and the arms wrapping around the die.

One important thing to remember is that you never want to carve away the corners of the die. You can carve into the faces, but the corners are what make the die roll evenly.

Because of that, I'm having my octopus arms running along the corners, This also keeps them away from the center of each side which is helpful for having a place for carving the numbers in each side.

The larger your die, the more space you'll have for art and numbers. The head and the webbing between the arms take up a lot of space and don't leave much space for numbers.

Start by scribing your shapes in gently. This will give you a chance to correct errors by melting wax into the face of the die if needed. Slowly carve deeper if it looks like you're on the right track.

I usually carve in my numbers last, but this can also get me into trouble, when a large number like the 20 in this case lands on a side that doesn't have much space on it.

This step isn't strictly needed, but if you worked very hard on your die and the cast fails, you'll need to carve it all over again. If you make a mold of your carving, you can make more wax positives and keep trying.

Get out your mold making material again. I use silicon caulk because it's readily available but it's not ideal. A pourable mold material is going to give you fewer headaches. If you only want to make one die though, you might want a material that you can get locally.

Put your nitrile gloves on.

I squirt a pile of silicone onto a clean surface and then add a few drops of food coloring. The color helps me identify the mold and the little bit of water in the food coloring starts the curing process of the silicone. This process can throw off strong ammonia fumes so make sure you're in a well ventilated area. Mix thoroughly with your paint stick or spatula. The mixture can cure in as little as ten minutes so don't dilly dally.

Coat the interior of your box or cup with your mixture. Next coat your carved wax die in the mixture and lower it into the box. Fill in any remaining gaps with the mixture or if you didn't mix enough, inject straight silicone into any voids.

Once the silicone is cured, remove the mold from the box. There may be a strong ammonia smell, if there is, the mold may not be fully cured. Check for any voids that wax could get into and fill them with silicone. If you did a good job, there shouldn't be any, but you'll see in the pictures I didn't do a good job and had to fill a lot of voids. If you have to do any repairs, put the mold back in your box and let it cure for another day.

Trim off any excess mold material so you have a little rubbery brick.

Next cut into the mold in a zigzag pattern with your exacto. This allows the two halves of the mold to match up properly. You will probably damage your original carving in the process of freeing it from the mold. That's ok, you can make more of them. You may need to gently pull the halves apart to cut all the way to the wax with your blade.

Once you've freed your original from the mold, cut a small hole in the highest corner to make a channel for wax to pour in.

Get your new mold ready to take wax by putting it back in the box.

Melt some wax and pour it in. Don't heat the wax up too hot. High heat can damage the wax and the hotter it is, the more problems you'll have with the wax shrinking away from the walls of the mold. Tap the side of the box to let air bubbles rise to the top. You can also rotate the box to try and shift any large bubbles.

Your new positive might not be perfect. Air bubbles may have stuck to the inside. The wax might have shrunk. The mold might not be perfect. Sometimes small details are lost.

If there's missing wax because of shrinkage or air bubbles, add some wax to that half of the mold and reinsert the die. Wait ten minutes and see if the added wax fixed the problem. Be careful of the hot wax squirting out when you reinsert the die.

For small details that didn't fill in well, you can recarve details like cleaning up numbers. Numbers like 4, 6, 9, and 8 can be problematic if they're carved too deeply. Only carve numbers deep enough to be clearly seen.

At this point, you'll need to make wax sprues so that the metal can get into the final mold. These are tubes of wax that you'll attach to the wax positive. I normally attach the sprues to the vertexes of the die. I melt the tip of the sprue and then melt a little bit of the die vertex. There isn't usually a lot of space to make this attachment so it can be weak.

Get an old soup can that's big enough for the die and its sprues to fit in.

Mix up enough sand and plaster (half sand half plaster of paris mix) to fill the can almost to the top. Add water until the mixture is runny. This mixture can harden in minutes so work quickly.

Coat the wax die in the mixture. Make sure it gets into all the numbers and fine details.

Pour a quarter of the plaster sand mixture into the can. Insert your die, making sure there are no air voids. Continue pouring in the mixture around the die. Make sure to keep the top of the sprues

The plaster will harden quickly but it's best to let the mold dry for several days to a week or more. The water in the mold is now your enemy. The longer you give the mold to dry, the better.

Here are two molds I made a week ago. I start by placing them upside down in a pan over the hot plate. You could place them upside down in a crock pot or burn them out in an old grill that you weren't going to cook on anymore. The goal is to get the wax to melt out of them. Another possibility would be to cover the opening in aluminum foil and put the mold next to a camp fire.

Depending on your heat source, the wax can smoke and potentially catch fire. I keep a fire extinguisher nearby but so far I haven't had to use it. I also have a powered exhaust vent in my workshop to suck out smoke.

Once the wax has melted out, flip them right side up. Make sure nothing falls into the mold. It's very hard to get things out once they go in. Now you want any residual water or wax to evaporate.

I use either welding gloves or tongs to pick up the cans while they're hot.

The longer you have the molds heated, the better. Both the wax and the water in the plaster are big problems for metal casting. I keep the molds on the hot plate on medium for half a day and they still aren't done cooking out.

The last part of the bake off process is done in the metal melting furnace. Light the furnace. If you're using propane like me, I only run the burner at 10 psi at this point.

Put the cans in the furnace.

The cans will get red hot, that's fine. Rotate them with tongs periodically so they heat more evenly.

If you got the plaster too hot, it will start to crumble. I used to worry about that happening, but so far doing it this way has never caused the mold to fail for me.

There are three things to look for to know when the molds are ready. If you can see vapor coming off them, that's water, and they're not ready. If you see smoke or flames, that's wax burning off and they're not ready.

Recently I've noticed that the top of the plaster turns black as the molds are baking off. This is wax residue that partially burns and deposits itself on the top of the mold. This too will burn off as the baking process happens. Once the top of the mold has turned white again, the molds are generally ready.

All of this is difficult to get pictures of because of the temperatures involved.

There are a number of Instructables on how to build a metal melting furnace and to get into that would be too much to cover here. I'm assuming you have a furnace and are looking for a nifty project that you can do.

I keep my molds near the tweer of my furnace to keep them warm. The warmer the better. If they cool off too much it's said they can start absorbing moisture from the air again.

Once my metal is nice and melted, I pour into the molds.

Once the mold and the metal in it have cooled, cut the rim of the can with shears or tin snips and then tear the can open with pliers. The can was weakened by the baking process earlier and will rip along your cut with some effort.

Once you get the can opened up enough, use a hammer to hit the side of the mold. It will break up the mold and pulverize it. If a lot of the plaster is sticking to your cast, dip it in water and it will fall apart easier.

One of the casts I tried here failed while the other worked out well enough. On the cast with the single sprue, the bottom two sides of the die didn't turn out. The double sprue cast worked out though.

Cut off the sprues with a hacksaw or bandsaw and file or sand off the remaining bumps.

I run the dies under a wire wheel and clean up any minor casting problems with a Dremel tool.

Paint the numbers with the colors of your choice using a toothpick or thin wire as your paintbrush.

If you're curious the mega chonk dice are a bit over 7 ounces or 200 grams of aluminum. The smaller aluminum dice are about 1.7 oz or 46 grams. The brass die is 4.8 oz or 137 grams. The brass die seems like it's going to break the table. Maybe one day I'll make a brass mega chonk

This is just my method of making dice. There are many other ways to get to the same place. If you have questions, please ask. If you see something I'm doing wrong, let me know. I'm always learning. I hope you picked up something useful for your project and I hope you make a die of your own!