Al Azom (cool name): Go to Spearboard. These guys have reported on hundreds of homemade spearguns and some not so homemade. However, I assume you want to make a speargun because you can't afford to buy a factory gun? You see, most of the spearos don't actually make a gun. They make a nice wood stock and fit it out with expensive components from small manufacturers like Alexander, Wong, Kitto, Riffe, etc. In the USA, there are more "homemade" guns than can be counted. Somewhere, somebody has made a cheap gun. Hey, wait a minute, I helped a friend build a couple of guns using homemade triggers, and one with a Biller trigger. My suggestion would be to build a wood gun using the Biller trigger. If you want to build a trigger instead of buying one there are pictures and details of a neat trigger with plexiglas housing. Do a search on Spear Board.