Chuck Bjorgen
I remember watching your video using the power sander to flatten a stone. I’ll probably not have need for that but it’s good to know about. Your thought about using Simple Green to clean the stone was good. Just 30 minutes and it brightened up the light colors of the stone which I’ll now put to use.

The plastic laminate sheets seemed to be recommended by Lee Valley. I checked the used sheet more carefully today and found no sign that the grits were embedded in the plastic. There were serious scratches in the plastic for sure so I suspect their use is to protect the glass from being abraded. My 5/16” chunk of glass was bought for this purpose many years ago so I was happy to protect it. A simple project is done.