Below is some examples of my custom etched glass done for various people with low cost equipment. Hopefully, this will spark some creativity and is only the starting point to etching glass. More skill and technique will allow you to create 3 dimensional carvings from the back side, shading to reveal gray scale effects, and a mixture of both. This is done with the sandblaster method and as you can see has clearer etchings in comparison to the hobby cream method. Seek the equipment section about sandblasters for glass mugs.
Colleen's Glass Etching -Colleen provides a great glass etching service for any occasion such as weddings. Just tell her what your thinking and check out her work on the website.