Lydia also had a 100 days of school project. She went a little more traditional, but still very creative, doing a varaition on a project she remembered from preschool.
She got a canvas and started by gluing 100 crayons round it, framing the edge.
Then got a hair dryer.
the dryer melts the crayons and you just let them drip, perhaps moving the canvas around a bit to mix and help direct streaks. The end result is absolutely beautiful.