Hey Pat…I like your ambition! I have fixed several grip scales, obsolete buttplates and even some Ruger Mark II frames using Marine-tex two part epoxy putty. You can build up a gouge, corner or what you have to deal with and then sculpt it out to match contours, grooves/borders, etc. It sands well and polishes out to match surfaces…you can even checker it if you have to. For the black grips, etc I use the Grey color and tint it to a solid black with Mixol Tinting paste (#1 is Black) it doesn’t take much and I use different tints from this same brand to color match other epoxies I use for repairs, bedding, etc. If you want to make a mould it will work well…beware of air bubbles. I use Isokote 1000 Release Agent when I use this for bedding…have yet to have it stick.
Hope this helps…Have fun.
John
