This tutorial will teach you how to make your own, fully customized SFX prosthetic makeup pieces! This surprisingly easy and affordable project can turn a costume from basic to extroardinary.

If you want to make a truly incredible Halloween or cosplay costume, you will probably need to use SFX (Special Effects) makeup. For detailed, realistic illusions, FX makeup artists use prosthetic pieces to their advantage, usually made out of latex.

Latex prosthetics make it easy to create illusions of elf ears, scars, open wounds, horns, and more. However, if you buy them cheaply, they are often ill-fitting to both the costume and the artist! If you want to take your SFX makeup to the next level, try making your own prosthetic pieces!

My Process

In order to take you through the process, I am going to be making a custom prosthetic for my Halloween costume: A set of brand scars with spooky symbols. You are welcome to follow along and copy my designs, or use the techniques I teach you to create a prosthetic of anything you can think of!

Step 1: Supplies and Tools

Supplies:

Modeling clay
Any modelling clay you find in a craft store should work. (It should NOT be oven-bake or air-dry.) For this tutorial, I used Plastalina Modeling Clay. The color of the clay should not matter. I prefer to use white.
Plaster of Paris
Any brand will do, and you won’t need much.
Liquid latex
Look for anything that mentions SFX makeup.
Vaseline (optional)
This will make it easier to remove your prosthetic from your mold.

WARNING: If you have a latex allergy, DO NOT use liquid latex! A good resource on alternative "fauxtex" materials can be found here.

Tools:

Sculpting tools
You shouldn’t have to purchase these. I like using kitchen utensils and random office supplies!
A disposable waterproof sheet. Examples: Tin foil, plastic wrap, and wax paper.
A bowl
Water
A mixing implement
(Optional) Disposable plastic cups

Once you have everything collected, prepare a flat space to work and lay out your waterproof sheet of choice.

Step 2: Sculpting Your Prosthetic

Now that you’ve got your tools together, you can start on your project!

For this step, you will open your packet of clay and start sculpting! Whatever shape your clay takes will be the final shape of your prosthetic piece. You don’t need prior sculpting experience, just play with it, have fun and be creative!

CAUTION: Remove any rings before you start sculpting. While not impossible, clay can be very difficult to get out of tiny crevaces in jewelry.

Prosthetic Sculpting Tips

If possible, look up some photos of the desired effect. You don’t need to copy them exactly, but it can be very helpful to have a reference.
Don’t only use your hands to sculpt! Almost anything can be used to shape clay, and give it texture.
The back of a spoon works great for smoothing out and hiding where two pieces of clay are joined, and tapering out the edges of the prosthetic.
Try not to have your edges be straight, uniform lines or sharp corners, as they are more difficult to blend in when you apply the prosthetic.

My Process

For my branding scar prosthetics, I ended up using only two tools: A butterknife and a washcloth. I used the butterknife to cut patterns into a thin piece of clay, then used my fingers to close up the cuts in a raised fashion, simulating scarring. Then, I carefully dabbed with the washcloth to create the rough, mottled texture I wanted. (This took some experimenting to get right! Don't be afraid to try sticking different things to your clay to see what textures it creates!)

Step 3: Pouring Your Mold

At this point, you should be satisfied with your clay model and ready to create your mold.

Working with Plaster of Paris

Craft plaster is rather thin and “runny” before it sets, so prepare your space accordingly.
If your model is small enough, you could place it in a disposable bowl. Otherwise, just make sure your workspace is large enough to accommodate the plaster running.
One method I like is using card-stock strips and tape to create a “fence” around your mold, as seen in the above picture.
None of the above will affect your final prosthetic.

When you have your workspace ready, take the plaster of paris and mix it with water according to the instructions on the packaging. Mix thoroughly to avoid any hidden clumps of powder.

WARNING: Do not rinse plaster down your sink, as plaster can damage your pipes!

Now, slowly pour your plaster over your clay model, making sure the plaster has enough time to disperse any bubbles. Make sure you cover the all of the clay with between 1/4th inch and 1 inch of plaster. (7mm to 26mm)

Once the plaster has dried and cured (24 hours for most plasters), you can carefully peel the clay out of your mold. If your design was especially intricate, you may have to carefully scrape out the extra clay with a needle or toothpick.

CAUTION: Do not wash or rinse your mold once it has dried! Water will damage the plaster!

My Process

After laying down a tinfoil surface to pour on, I used cardstock, tape, and scissors to make borders for two out of three molds. I poured one mold free, in order to show you what would happen. After securing all my clay models, I mixed the plaster of paris and slowly poured it over the models. 24 hours later, I peeled out the clay, revealing my plaster molds.

Step 4: Casting Your Prosthetic

If you’ve made it this far, you have a dry, cured mold and you are ready to cast your prosthetic!

Again, start by making sure you have a clean space to work, where any spilled latex won’t hurt anything. Set up your mold upside-down, so you can pour the latex in. (If the back of your mold isn’t completely flat, you can use leftover clay to level it.)

WARNING: If you have a latex allergy, DO NOT use liquid latex! A good resource on alternative "fauxtex" materials can be found here.

Now, if you have vaseline or something similar, apply a thin layer to the inside of your mold. Next, pour your liquid latex into the mold.

Once the latex is poured, you again wait another 24 hours for it to fully harden and set.

After 24 hours has passed, gently peel the prosthetic out of the mold. Patience is key here. It may take a while, but it will come out.

Congratulations! You have created a custom makeup prosthetic the world has never seen before. You also now have a mold, allowing you to repeat this step to make more copies of the prosthetic.

My Process

Finally, I laid out a clean workspace and poured my liquid latex into my molds! I didn't use any sort of lubricant for the mold, I just poured latex directly on the plaster. After about 24 hours, I gently peeled out the dried prosthetics!

Later, I used spirit gum to adhere the prosthetic piece to my skin and used Halloween makeup to paint it to look like a real scar.

I hope you enjoyed this tutorial and can use it to make your next costume even more awesome!