Finally cased my Colt Pocket Navy

[Maccab]

If you follow me, you'd try and create a circular cavity which the magnet sits in, this cavity would be in a fatter part of the material than the grip plate i.e. it would sit in the frame part, although the metal magnets sides would probably be better against the metal frame as a stop like.

Be ways, anyway glues very strong.

[45flint]

I would think no more than 3 locator pins per side...? Hope you come up with a standard template on the first try, it would be frustrating to lose grip compatibility due to locator pins.

The pins would not be to fit grip o gun, only to attach magnet to grip.   Spesser makes very good grips and he uses small screws plus epoxy to attach his internal grip guides.   

[ikoiko]

Don't remember the site, but have seen rare earth magnets with a hole and concavity already for accepting a screw.

[Maccab]

Maybe you could stick the flint to a sheet of metal like a veneer somehow if you could sand one side down then attach the magnets to the metal.