We are part of an art coop with a group of other moms with kids Lincoln's age. Each week we rotate houses and do a different project. This week we hosted and the kids made these melted crayon sun-catchers. It was a quick project, which is good for short attention spans, and pretty kid friendly. Yes, it involved the use of a hot iron, but I do believe it is important for kids to use real tools under adult supervision. I think it teaches them safety and allows them more opportunities to explore when not limited to kid's tools. Teacher Tom talks about how using hot glue guns opened up new avenues of creativity with his preschool students here.
To make these sun catchers, just gather up some crayons, a pencil sharpener, waxed paper, an iron, and 2 towels (or paper bags).
Peel back the paper on the crayons and sharpen them over a plate/bowl/whatever. Group the shavings by color, if you like.
Tape a square of waxed paper to the table and allow your child to place the crayon shavings wherever he likes on top of it. Keep it to a thin layer, or the crayons won't be translucent when they melt.