While I was thinking of something to make with some nice new split pins (brads), my daughter used them to craft up a cool cardboard car.
Without any suggestion or guidance she worked out how to make a car with moving wheels. She used toilet paper rolls for the wheels, and another cardboard tube to make the body for the car. Some bits of card recycled from some packaging was used to make the car shapes. She also made some circles to go on the wheels for the split pins to go in.
I cut the cardboard rolls up where directed and glued all the bits together. The car bits were decorated with colored pencils.
The wheels worked really well and turned easily.