My tanks are homemade jobs, but glass is glass (unless it's tempered glass, but exo terras don't appear to be http://www.dendroboard.com/forum/beg...exo-terra.html).

I used one of my practice holes from yesterday as a template to help start a new practice hole and it worked like a charm. Much easier and no skipping. My main problem now is when the hole is nearly complete I'm having a hard time going slowly enough when about to go out the other side so the back side of the glass is chipping off slightly. Not in a structurally hazardous way, but it looks messy.

To be honest I have no specific plans at the moment for what I'm going to drill for a real use. I originally wanted to do a waterfall with a canister type of filter externally so I figured being able to drill glass would be handy. It also gives more options for types of fasteners, handles and other things I can use on homemade tanks, and I might look at getting a larger bit to put air vents near the bottom of tall vivariums.