This is a HUGE model of the 4-8-8-4 Big Boy, an American steam locomotive used by Union Pacific Railroad from 1941 into the 1960s. A special project commissioned by MakerBot to test limits of 3D printing, it was created and assembled by Paul Fischer. Fischer spent between 700 and 800 hours drafting and another 1,000 hours 3D printing the locomotive on a MakerBot Replicator 2 Desktop 3D Printer. The finished engine is six feet long.