The C4 was developed for the US Navy after WW2 as a successor to the Liberty and Victory ships. The ships would largely be owned and operated by private shipping lines but could be requisitioned in time of war. This happened in the Korean War. I believe that some are still sailing.I have printed a few of these in PLA at 0.25 mm layers at very slow speed so that the finer parts do not distort. Masts can be made from 1.2 mm brass wire and balsa wood blocks. Holes are incorporated in the decks for masts to slot into.