No secrets here! I sculpt them in plastilene clay, which is a non-hardening medium. It really holds hard edges well, and allows for reworking with proportions, and details. I do work in sculpy but find it much easier to do mechanical detail with the clay.
"Better to have a gun and not need it, than to need one and not have it." -Clarence Horley
So how exactly do you cast them. If the clay medium your using is non hardnening seems like it would be hard to make a mold on them. I'm not that into casting though so probably missing something simple there.
Dose that mean that you make one peice molds? I use plastilene for making the seem (between halfs) in the mold, if the sculpt is the same material wouldn't it stick?