I've actually taken the time to do some engineering sketches of the projectiles, and althouh they would not be too difficult to reproduce in a manner that worked, tooling for it would be prohibitively expensive for an individual. Perhaps a few of us could get together, make a few prototypes, do some market research, and see about commercial manifacture of a small run. They look like they would be relatively easy to make by hand with the right tooling.
I will say that because of a design flaw (easily overcome) they were very inacurate, and didnt have any apprecialble energy until they were 20 meters or so from the muzzle.