I got a 2" Thumb Blaster from Lucas Raymond at the Arm Assassin Strength Shop. Besides being a really good thumb training tool, flipping it around and using to train crush grip, is an almost perfect replication of the crush grip used on a pistol. Neutral wrist, minimal skin stretch, no rotation and minimal thumb involvement. It's easy on the skin and joints, and carryovers well to a firing grip. For $35 IMO it's one of the best implements out there for grip training for pistol shooting.