Derma wax could be used but the bad thing about that is it will start t melt and get soft just from the heat of your body, it's only good for short term use. The only other thing that I can think of that would work like the derma wax would be nose and face putty. Still the best thin would be latex and toilet paper, unless you want to get into making appliances.
you can use gel glue apply a think layer let it dry on your skin, then you can make holes (you can get a q-tip and apply blood or dirt in the hole and under the glue) or peel off to make a rotted flesh look. you can mix toilet paper with fake blood to make a chunky gore look or make a gelatin applicant. you can also mix gluten with water and red food dye and make intestines, the longer you let it sit the more realistic it looks, then when you squeeze them it will look like blood is squeezing out