The one piece cannon barrel is made by pouring high quality virgin black powder polyethylene into a fine detailed cast aluminium mould with a sandblasted finish then placed in a computer controlled oven and baked at high temperatures until molten. The mould is rotated through multiple axes so the molten polyethylene evenly distributes and coats the whole interior until it builds to a thick wall. The computer programming then switches into cooling mode and the cannon barrel is hardened and precisely formed.