To support the palm shelf, I drilled and installed (5) 3" drywall screws; cutting them down to 1/2" on the fat side, and a 1/4" on the thin side.
Here's the frame again, mounted up and ready to pour the casting resin. I used Alumilite's Amazing Casting Resin.
I didn't get pics of the pour. I took a short cut that came back to bite me in the butt. A little bite; but a bite none the less. I depended on small strips of the metal duct tape to seal the edge between the wall of the mold and the floor. It leaked in one spot. Hindsight, I would have used some silicone to seal the edge.
Here's a pic of the grip shortly after the resin set up (roughly 15-20 minutes). Here you can see the effects of the leak; as seen by the ridge left from the outside walls of the mold. The palm shelf doesn't quite touch the Pachmayr grips; but it isn't very noticeable.