Can't help you with the light sabre. We do have an exotic weapons forum here on GBO, you might want to post your request over there and see what happens. You might also find one of those Star wars discussion forums and post a request for help.
The plans are posted for the Florida bowling ball mortar. That's a pretty simple design and is pretty easy to reverse engineer. Every thing you need to build the gun is in the first post. There are concerns about that design.
First Bill said this mortar has tendancy to flip over on its back when fired. That can be corrected by a different carriage design. The trunnion should be on or in ahead of the front to rear center line for better stability.
The powder chamber doesn't meet the recommended safety standards. The walls of the chamber need to be the same thickness as the diameter of the chamber. The powder chamber is 2" in diameter and 2 1/2" deep. Minumum outside dimensions for that size chamber is 6 inches in diameter and 4 1/2" long.
The powder chamber on the outside doesn't appeal to me, but there is nothing wrong with it. The gun looks like pre 19th century European grenade mortars. If I built this mortars I would add some decorative bands on the barrel to look like moulding reinforcement bands.
The Pressure tank needed to make the expansion chamber for a bowling ball mortar is the 300 CF, DOT 3AA2400 made by Taylor Wharton.
Bill Tyrrell sent these pictures and drawings of his bowling ball mortar.
The mortar is made from an old O2 tank. Bill says you need the one that is 29 1/8 inch in circumference. Cut it to about 18 inches. While cutting it also cut the valve stem off the back leaving a 4 inch flat for welding on the Chamber. The chamber Bill made is a piece or 4" x 5" round stock with 2" x 2 1/2" deep hole for the chamber.
Bill milled a flat and rigged a slap hammer on the side of the chamber . His nipple is made from 1/4-20 bolt
The Trunnion is a 2" solid round with a flat milled on the side to fit the bottom of the chamber. The trunnion is welded to the bottom of the chamber.
Ball warns not to make a carraige like his. the trunnion is too far back and the Mortar has a tendancy to turnover.
Here is a drawng from Bill for building the mortar. I have left it sideway so you can print it out and it will be large enough to read.
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Thanks Bill for sharing it with us
