Another coilgun..
In the 1967 Eric Laithwaite described how to make a linear accellarator at home, including a simple half-phase 3-phase converter to power it using normal house power supplies (I think it was actually cut to 16v first, for safety reasons). Of course, it would probably be illegal, even in the US, due to technically being an automatic weapon (anything conductive placed inside the coils would be accelarated, with a single barrel fire rate theoretically exceeding any machine gun, due to the possibility of having several shots in the barrel at once). A 16v, 50-60Hz version probably wouldn't be particularly effective, but a long-barrelled, highvoltage version has be considered for space launch.