A hard as they may seem at first glance to make a key is quite simple. All I did was take a 2x4 cut to size, used a back piece from an old scrap computer (one of the little slats of metal used to cover the pci/isa slots when not in use) for the paddle and 3 screws one to make the left contact, one for the right and one to hold the rubber band in place. I used a rubber band to keep the metal neutral between the contacts.

For the conenctions I took an old stero audio cable hooked one wire to the metal slat, hooked one wire to one post, and the last wire to the other post. when the metal slat touched one screw a dit was formed when it hit the other it was a dah. It was rude it was crude and it worked. My first cw contact was with this key, 7wpm :-). Here is a picture to go by.