After print the original balloon, I was very excited to watch it race along the floor. My balloon racer had a few problems that prevented me from moving. My balloon racer was very heavy and was not air tight. After adding rubber cement, the craft moved 3 inches Lighter and more air tight than the original balloon car. Print with 3 solid layers & 0.2 infill. Add a Lego man. Drill 3mm holes and add your own wheels. I used M3 bolts for my axles. This Balloon Car moved about 24in with a 9in balloon. I challenge you to design a better Balloon car. Rules:Everything must be printed (Except Axles) Must use a 9in Balloon or smaller