Hello

I have a wood router that I have not used for stone before. On the side I teach primitive living skills, including friction fire/bowdrilling.
Attachment 241728

I want to make several dozen sets for the classes i teach and am wondering if I should use the router to carve/grind a shallow ~1" diam. and maybe 3/8" deep well in each small stone (each of which would be clamped onto the router table of course). The other options are to use a dremel or a rotorary hammer/drill. any suggestions about:
  1. what type of tool would be best, router, dremel or rotary hammer?
  2. what type of tooling would be best for the chosen tool, diamond burr, fluted cutter with diamond (or carbide?) or masonry bit or ???

Thanks for any help here.
Dan