The files for them are now freely available. I foresee a lot of Darwin Awards. Making a gun is not actually all that difficult. Making one that won't explode when you fire it has been a project of the centuries, and takes considerably more skill and luck. It gives a whole new meaning to "You'll shoot your eye out!" I would not be surprised if exploding plastic guns do a great deal more to discourage people from making them than the government ever could.