How can one make a prosthetic neck slit, one similar to sweeney todd or halloween?

Question

just doing some research for our upcoming movie

H A R V E Y

Answer 1

model what you want it to look like in clay, then get some liquid rubber, latex, silicon, etc. and pour it over the clay.  Let it set and then pour in the compound that you want to use (probably more liq. rubber, latex, etc.) then when that comes out, you can paint it and gore it all up....have fun!