Shots of the various self-made weapons seized by Russian army and police in Chechnya. There is even self-made machine gun.
Where there's a will there's a way, and these are the way to obtaining better weaponry.
Do they work? Are they reliable?
Let me put it this way--if someone got the drop on you and was pointing one at your head, how inclined would you be to bet your life that they'd do nothing, misfire or blow up in your assailant's face?
If the answer is "Not very," then we've eliminated the need for anything but the most rudimentary of tools and materials.
[Via Featherless Biped]