I thought this was a great idea!! I can remember when Jennifer was in school and had art projects that she was working on at home and had to take back to school. She also rode a bus.
Cardboard mailing tube with two end caps
Duct tape (comes in Colors)
1. Make the strap by unrolling about 40inches of duct tape and laying it sticky side up on a table. Place a second strip of equal length on top of the first, with the sticky side down. Carefully press the two together.
2. Attach the strap to one end of the mailing tube with duct tape. Measure the strap so that it'll fir confortably across your child's chest then cut off the excess and attach this end to the tube with tape.
3. Wrap tape around both of the tube's ends a few times. Then have fun decorating the tube with markers, etc.