Etching a complex design

Hello,
I have started some simple glass etching, and right now I am simply
using Armour Etch on top of contact paper. I trace a design onto the
contact paper, and then cut out areas out with a razor. It's
rudimentary, but it works. However, the design can only be cut so
finely before I either go insane or the contact paper stops sticking.
Does anyone know of some (DIY) methods of etching a more complex
design? Are there some photo-sensitive etch-resist substances I can
use, similar to the emulsion in screen printing maybe?