One of the trendy things right now with crafts/decorations is where Christmas lights are put inside a glass block. The glass block is then has vinyl put on it or some other decorations. Click the picture below to see lots of examples at Etsy.
My wife wanted to do this with a bunch of women at Church, so I volunteered (actually, my wife volunteered me) to cut the hole in the blocks. I told her I didn’t know how to do it, but that I’d be happy to help. She asked around, and one man said he had what we needed. It ended up it was a Dremel bit to cut tiles. It worked, but was slow, and the bit overheated easily. We then spoke to another man who said he had a carbide bit that would work. It worked, but was a lot more powerful and ended up breaking two blocks out of 5. We finally spoke to someone who had done it before. The bit is actually a diamond hole saw (see below). We kept the surface of the glass block wet, and it went through like butter. Very nice!
