Accelerator attack DIY:
1. Buy a shotgun in a gunshop. I suggest Remington Model 870 because FPS Russia says it's useful in a doomsday situation, and he says it's cheap.
2. Load the shotgun by pushing (a) shotgun shell(s) into the hole.
3. Put your left hand on the receiver, put the stock against your shoulder, grip the pump-handle with the right hand, and pull it, then release the handle. It should eject back to it's normal place.
4. Point the shotgun at a human head in point-blank range. It can be either yours or someone elses. Normally I'd just point the shotgun at a brick wall or a watermelon instead to evade problems concerning law.
5. Pull the trigger.