From scratch, odds/ends out of the wood scrapbox, stuff found at the marine/industrial supply, drawn over mandrel 3/4" wall 1" dia. steam tubing. Hardest part was cold forging the trunnion caps from 1/8" X 1" width strap steel. Tricky to get them to seat tight on the trunnions. 500 gr. Fg Goex, six squares of toilet tissue (two ply) . . . shooting blanks, but it does fire a lead ball or C Cell battery, nuts, bolts, nails, rocks . . .