One technique that I've learned watching the Bullseye Glass videos is making "parts sheets". A part sheet is a pattern sheet that you design yourself. It's also called collage glass and you can buy some cool patterns. I'm having a lot of fun playing with making my own parts sheets. So far everything I've made has been on a clear base but you could do it any way you wanted.
I can use my painting stencils and glass powder to create stencil patterns on glass.
This one was covered with red powder and the pattern was marked with a razor blade.
This one uses stringers, large frit and some powder frit. I've made several of them and finally used one in a project. The sheets generally fuse totally flat but the sheets with stringers often do not or have to be fired twice to get them flat.
This dish is 5" x 10" and has a parts sheet made of stringers. I like it a lot.
Since the stringer sheet wasn't totally flat I knew that I would get bubbles but I also knew that they would be trapped between the stringers and I thought it might look pretty cool. I think it worked out just fine.