If you take apart GarE Maxton’s 40-45 lb. (18.18-20.45 kgs.) puzzle sculpture, comprised of over 100 pieces which took a year’s worth of precision machining to produce, you can assemble from a number of concealed parts the single shot .45 caliber muzzle-loading pistol seen below.
6:46 video of disassembly.
8:22 video of assembly
Hat tip to Brian Barrett via Karen L. Myers.