I just got a tipman today and had already considered how to form the receiver pistol grip section. The reason I'm considering this is to make it look like a British sterling. So I want reshape the trigger guard, the position of the cocking handle, etc. etc.
if I discover a easy method of doing this I could contact you. Even though I am a former machinist run nothing is ever as easy as it appears. Here are some pictures of my tipman patchett submachine gun.