There was a guy who spent something like $50 building two zip shotguns from parts he bought at home-depot, turning them in at a buyback program - using the money to buy real guns.
I have often thought about short pieces of pipe and using scrap lumber to build really cheap pistols and giving them out to homeless people in the vicinity of a gun buy back.
THE N.R.A AND OTHER GUN ASSOCIATIONS AND MILITIA; SHOULD OPEN COMPANIES ASSEMBLING SCRAP PARTS OF BROKEN GUNS INTO ONE THAT APPEARS FUNCTIONAL, SELLING THEM TO CIVILIANS FOR $200, THEN THE CIVILIANS CAN SELL THEM TO THE GOVERNMENT BUYBACK PROGRAMS FOR $300 AND BANKRUPT THE WHOLE PROGRAM