Glass etching is one of the easiest crafts one can do, in my opinion. Anything you can draw or trace onto some contact paper and cut out with a craft knife can be etched onto a mirror or piece of glass.
For a wedding gift for my sister in law, I etched this glass mirror.
Simply, I laid contact paper on the mirror, smoothing well to make sure no air was trapped underneath. Then I traced the fairy image from a printed image I found online (slightly altered to suit my taste), added the bride and grooms name and wedding date in my own handwriting, and cut it all out with an x-acto. After applying a nice thick coat of Armor Etch and waiting about 10 minutes, I washed my piece and removed the contact paper. Ta-Daaa!!!