Steve, 1/2" is thick enough. A 3 1/2" X 3 1/2" square will do Colt & clones and Ruger grips. After I fit the blank to the corner of the grip frame and drill the hole for the index pin I trace around the frame with a fine line magic marker and saw out the blank to the outside of the line. I shape them with a Dremel and a 1/2" sanding drum. I use a coarse drum until its almost shaped, switched to a fine drum to get really close, then go to garnet paper wrapped around a 7/8" dowel to get the final cut. Then I hand sand with 220 and 320 grit, use alcohol to raise the grain and sand until I can't feel any whiskers and then apply finish , rubbing it off until between coats with 0000 steel wool until the pores are filled. Then about three coats of finish rubbing lightly between coats.
The Dremel makes a real mess. Dust everywhere. Wear a mask.
