This is my custom launch dolly STL I designed for the C-17. Due to the unique shape of the bottom of the aircraft, it requires its own custom holding brackets for holding it securely in place during takeoff. Measurements: Base: 9"long x 7"tall x 9"wide Wheels: 4" wide diameter Materials needed: 4x Skateboard Bearings 608 ZZ, 8x22x7 miniature ball bearings 4x Nylon Insert Lock Nut M8 - 1.25  4x Hex Nut M8 - 1.25 4x Oval Phillips Machine M8 - 1.25 x 35 This dolly works fanastically for takeoffs and rolls like a breeze thanks in part to the wheel bearings I use in this model. They are actually designed for use in a skateboard. I used 608 ZZ Skateboard Bearings, 8x22x7 Miniature Ball Bearings which can easily be purchased from Amazon or your local skate shop. The rest of the hardware can also be easily ordered from Amazon or purchased at your local hardware store.  I designed a version of this dolly to be able to be printed out of regular PLA for the base and TPU for the wheels if you want rubber-looking wheels. I also designed a version of the wheels that can be just printed out of regular PLA if you don't have TPU. Another feature of the wheels themselves is that they can handle grass field takeoffs as well as solid surfaces. They are designed to be large but thin so they can cut through grass very easily.