1. Using aluminum foil, form several small trays with edges.
2. Squirt about three tablespoons of washable neon tempera paint into each tray. Place a car in the center of each paint tray, set trays on a cookie sheet, and freeze overnight.
3. The next day, carefully peel the foil from each car and set the frozen car “paintbrushes” on a sheet of poster board. At first the frozen paint will behave more like a crayon, making marks that don’t look anything like paint.
4. In a few minutes, the car paintbrushes will begin to melt and paint more freely. After some more time, the wheels will be free of paint. Bit by bit, chunks of frozen paint will fall off onto the canvas. These become frozen “speed bumps” for the cars to drive over.
5. Once all the paint is free from the cars, kids can smoosh the frozen bits under their hands, swirling all the colors of paint to make a rich multicolored canvas.
6. Wash the cars and get them ready for another go ’round.
