I lucked out and found pre-cut tissue paper squares on clearance at a craft store on the day before I was going to do a stained glass style project for Mother's Day. It might sound like a lazy short cut since tissue paper is not too hard to cut, but the 1000 perfectly cut squares were worth 3 times what I paid for them. The cool thing is that they have lasted through many projects over the past year and I have barely made a dent in the stacks.
Our project was to use mod podge to apply the squares to a small glass bowl that I found for about $1.50 in order to make a stained glass style candle holder. The kids had a lot of fun deciding the patterns and the finished product they were able to do it with only a little help. I recommend using the sponge brushes with the mod podge for a more even covering, but brushes will work. Make sure to clean them as soon as you are done though because once it dries, the brush is pretty much useless. Once the bowsl were dry, We put a tea light inside the bowl and then gave a baggie with wrapped candy and extra tea lights so their grandmas would be able to choose how they wanted to use them.
Since those gifts, I have also used the squares to make stained glass pictures on contact paper and for balling them up to make 3-d designs on cutouts. I also plan to make more art on glass, like vases or votive holders. I haven't found the squares at the craft store again but I did find them on the Oriental Trading site for a very modest price. We are finally out of our mod podge, so I will be picking up more of that at Jo-Anns with one of their great coupons or with the teacher's discount card.