Thrift stores are a wonderful resource for cool, interesting materials. I bought a bag of colourful clothespins for two dollars. I then went to the dollar store and bought some aluminum pie plates for a buck. This is the result!!! You can have the children match by a single color (put one clothespin on the plate; they clip to the outside) or start a pattern for them to copy. Their little fingers get a good work out, while their brains are busy organizing the pins.