To spray paint clothespins (or similar things), clip them onto an old cardboard box and tape the flaps up. they'll dry there and you won't have to worry about waiting for one side to dry at a time. Might use clothes pins for my traffic light next year!
Inspired by the melted crayon art, this splatter paint project can be used to talk with Kindergarteners about the weather in the spring, "April showers bring May flowers!" They LOVE getting messy with splatter paint.