[Rod]

Hi Trent

Be aware that cutting a hole will release stresses in the glass and ruin the figure on the mirror you have. It will need to be re- figured at the very least.

If you go ahead, I would recommend diamond tipped hole saws. I got some from eBay a few years ago. They work well and are inexpensive, just use plenty of water.

It's easy to to take a chunk of glass out on the rear side as the bit comes through so cut to within a short distance of one one side and then turn the mirror over and cut in from the other side.

Rod