I saw a bunch of these hanging together in a restaurant (Straw) by my house and decided to try and make one. I took the easy route and got the pre-assembled light socket and cord from ikea for pretty cheap. If you can't get to an ikea you can definitely take a trip to the hardware store and assemble the light socket yourself.
I've been a long-time instructable consumer, but this is my first time creating one so go easy on me please! Oh also, if hanging fixtures aren't your thing there are a bunch of other cool jar light 'ibles like this one