Sometimes it is fun to just gear up and doodle on glass with an engraving tool. Typically, the engraving happens after the artwork is complete, so the lines are much more opaque and free form than the lines in the carved work featured here. I like to use my flex-shaft with a tiny diamond ball tip, and the same water set up as the glass carving.
Engraving can be a little tricky, since it is free hand, and the artwork isn’t usually flat. However, with a bit of practice, it is a nice way to expand your options.