1. White Elmer's Glue. I haven't tried it on other white glues. I tried using the Washable No Run Gel, I'm still waiting for what it would come out.
2. Tissue Paper. Just your plain old tissues. Nothing special needed.
3. Foam/Brush. Or you could use your hands.
4. Foundation/Concealer. To give the prosthetic skin-like color.
5. Blower. This is somewhat, optional, it makes the job faster.
6. A base(Tray, Baking Pan, Any smooth surfaced platform. I used a book and plastic folder). This is very important, your whole project depends on this.

Once you reached four(4), or until you think it's enough, you apply another layer of glue over it, but do not dry it, put a layer of tissue paper over it and damp another enough glue to cover the tissue layer. I suggest that you do not pile layers of tissue paper since it would be hard for the glue to dry, and it would make the prosthetic not pliable.

After it dries, really really dry, it's time to peel it off. Every after you peel, you, again, apply/brush another layer of foundation below, to remove the stickiness of the peeled surface and to add the same skin-like effect. Keep doing this until you peeled the entire thing off.

This one's without the foundation/concealer. This was my first try. The surface is rough and the back is smooth.

EDIT: It came out nicely(not perfect though). I'll be posting a tutorial soon.  

EDIT: I'm going to try out the one made with gelatin mix and glycerine(though I   need to buy glycerine first) then I'll make the tutorial and review about it. *MEEEP*