I have an old pistol from the 1920's that has a small piece missing from the left grip panel. It wouldn't be much of a big deal except for the fact that the small piece that is missing has the job of holding a pin in place that is the pivot point for an internal spring toggle. Here's the beginnings of the repair. I glued a chunk of Mahogany onto the Walnut grip. Maybe not the smartest choice of wood but it was what I had on hand.