Most people that shoot IDPA (International Defensive Pistol Association) have probably seen this one before.
The basic idea is to take a standard size grocery bag, and with a few simple cuts you can get (2) IDPA targets that are very close to the right size. The only down side is that the finished targets are just a tad short, but well out of the scoring rings (0 point) so it’s not that big of a deal. The price of new cardboard targets is around 100 for $62.00 + shipping. So if you ask for paper on your next shopping trip the cost will be free.
This idea has been around for a while. The best I can tell it’s out of a book by Louis Awerbuck called "Hit or Myth".