An On3 frameless tank car (also known as a Dyke tank car). Trucks and couplers are bought but the body itself is printed. There are three ways to build it dependant on your printer and preferences including printing out formers for the tank and using plasticard for the tank skin.
The handrails and brake detail are made from wire as printing these is a pain and they end up massively fragile. The dome is pretty useful on home made tanks cars in its own right
The steps are very brittle.