I'm no expert in this field, I'm an amateur, but I can give you a blow-by-blow guide to how to create reasonably priced simple facial prosthesis for Halloween or other occasions.
I began honing my skills in a local haunted hay-ride(Trails to Terror at Highland Farms), they basically said "here's the stuff, you do it." So through trial and error I learned the way of making freaky prosthesis.
This instructable still under construction. Sorry I wish I had a more visual approach, and I will, for now it's going to be mostly words. Any suggestions are fully welcomed just shoot me a message. Thank you very much and I hope what's here is helpful.
Step 1: Procure the Necessary Materials
So, what you'll need is simple
Liquid Latex: This stuff isn't exactly cheap but you won't need a huge supply. I used about 2 liquid ounces of the stuff over the course of 5 separate haunts.
Note:It's a lot cheaper to buy in bulk online, it's cheaper online even if you DON'T buy in bulk.
I Paid: $19.99 American for a 4.5 oz bottle, I overpaid from a costume shop.
Toilette Paper/Paper Towel: This is found in just about every household, I even nabbed some from a local grocery because I was broke and didn't feel like stealing from family. This will provide a matrix for the Liquid Latex to adhere to and build on.
I Paid: Free
Foam Sponge(s): This is for the more squeamish in applying make up/liquid latex, as I have found plenty of success of using just my fingers(however is a larger mess)
I didn't use, but you can buy some for: 8 sponges for $4.50
Cotton Swabs/Artificial Webbing: These items are easier to manipulate than just paper product.
Mirror: I would greatly suggest using one of these, however useful this is in creating symmetry in your prosthesis it isn't needed especially if you're not making it on your face.
Blow Dryer/Large Fan: This helps harden the latex quicker, air dry does just fine though.
Clay/Flat Non-Stick Surface: This is if you want to make the prosthesis off of the face. I prefer not using these because it's a snugger fit if it's made on the face. Clay comes in useful when it comes to sculpting more complicated effects.
Vaseline: Not for a moisturizer or lubricant, this time you choose to use it as a way to keep all original hair on your body.
Make-up: to hide you can use whatever color you see fit,