ORIGINAL: rangerfredbob

instead of stones I'd use diamond cutters, I've gotten several of the cheezy $7 12V harbor freight rotary tool kits that come with a whole bunch of the diamond bits and have found several uses for them, like drilling a hole half way through my windshield to stop a crack from continuing across the window... and when converting to a different wheel type on my 1/5 scale car I had to drill holes for pins in the hardened rear axle stubs, lubed up an 1/8" diamond bit and drilled on through. Most of them have abrasive at the tips so they can drill straight in, and a bonus is they don't wear out near as bad as a stone