by transporting customers in a pressurized capsule propelled by a giant balloon. In its latest test, the Neptune-Excelsior spacecraft reached an altitude of 100,000 feet, or just over 30 km.

The build is based on an 11-inch party balloon that can provide about 11 grams of lift. This doesn’t allow for much leeway in terms of weight, so [masymachien] used hacked-up servos for the motors.