Check out this 17 year old who built his own fusion reactor. Here is the open source fusor research consortium. For more plans, research, and this
fusor built by Richard Hull. It's his fourth version - definitely worth
checking out. Essentially, all the atmospheric air is removed via
vacuum. Then you add a bit of deuterium gas, some high voltage and if
you got it right, bask in the glow of your own personal fusion
reaction. (Just watch out for X-ray leaks.) More here and here.