you need to source the printer, then the ABs plastic, then the bullets and other metal parts, then get the blooming printer to work with your computer (rolls eyes) while they are called printers, these 3d jobbies are huge beasts and the plastic has to be in the right conformation to work in the machine, you don't just open a packet and feed in the sheets. You can get a gun (and ammo) NOW off the net if you do your homework....honestly jim as a realistic thing to worry about its only just above the earth being struck by a meteorite.