If you get foam rubber about an inch thick,( two is better)specially made for forming wet leather you can put your wooden form on a piece of plywood,wet leather on top of that , the foam on top of that and another piece of plywood on top of that then clamp the entire works together using C-clamps or a vise.
I use a 10 ton shop press.
40 durometer foam is too stiff but there is some foam here that I have yet to try ...
http://www.knifekits...roducts_id=4293
I'm forming some cell foam cases today, just took the mold out of the shop press.
This will make two cases.
A few scraps of wood will work after forming but the molding process is easier when more than one item is being made and the finished product will look better coming out of a mold.