We adapted the mini-stained glass window project from Hands On History: Middle Ages using Sharpies and transparency film slightly. If you dab a Q-tip in rubbing alcohol (just a little bit!) and gently rub it around on the Sharpie-coated transparency, it will swirl and "bubble" like old-fashioned glass. We colored some areas with 1, 2, or 3 Sharpie colors, then did the alcohol thing and they look beautiful. You lose the marker lines, too, as a side benefit. Just go over dividing lines with black marker once it's dry and you have stained "glass"!