Anybody have a good way of making snap caps? Or easier just to buy them when the nylon "primer" is gouged out?

I made some for my 45/70 by loading up some bullets and cutting down some pencil erasers and glued them in for the primer.

Drill out the primer hole, tap it 1/4X20, screw in a nylon bolt.

I just fill the primer pockets with silicone.

Thanks all. I thought about trimming erasers and gluing them into the primer pocket. Hadn't thought about screws or silicone, though.