I've done it different ways. My next one, and I know there will be one will be to wrap the grip with cellophane, mold the grip, let cure. Once hardened I'm going to remove, then attach the mold with Duco. I want to see if I can make a decent removable section.
This is exactly what I had in mind. Cool idea with the cellophane. I have never heard of this for bows, but I know guys do it for other stuff. Here is what I was thinking.
Get my grip molded in just right with self hardening modeling clay over painters tape.
Remove clay and use as a negative mold.
Add cornstarch to silicone caulking and then mold over my clay, which will make a silicone mold.
pour in liquid epoxy (colorable if you want) to make a grip piece.
attach with epoxy or contact cement like a leather grip.
Cover with leather grip if it looks awful
This is where my mind went, but I want to make sure there's not a better way.