I used to have a couple of 14,000 volt capacitors that I picked up from the curb in front of someone's house. I was going to use them to build a coil gun. That was way over my head at the time, and I knew it, so I just kept them around until I got to them. I finally threw them away a few years ago. They were probably about the size of jerrycans and had great big contacts on the top to bolt wires to, separated from the body of the unit with big ceramic insulators. They were nifty!

And would probably handily kill someone if they were charged up.