The metal truss is a rare item that allows you to climb up it. Before, you had to put bricks on top of each other with a little room in between to make a ladder, which was very hard to do. Trusses used to be only found on silos, barns, and large buildings, and were not removable. It is about the same size as timber, and is only found in warehouses and large garages, such as the unique buildings in Kin and Military Outpost. It looks like a block of crisscrossed metal.