I was able to score some free windows being removed from a commercial building that was being demolished. Was all 3/8 plate glass.
I also had some file cabinet label holders that were clear plastic, I used them for lift handles in the past, attached them with some clear double sided VHB tape, not sure if I have any left. They were perfect handles though.
If you can get VHB tape from a hobby store, hobby lobby sells it, it works great for attaching anything to glass, or plastic. I use it to attach letter track to polycarbonate sign faces for reader board lettering. It is super sticky, and very durable. Its like double sided superglue on a roll.. and its clear. they also make it non-clear too, which is a lot cheaper. google it, 3M VHB tape.