Woo! At ECE a couple weeks ago I got a custom fit mouth guard. It's made by a company called Gladiator. When you order it, they take a mold of your teeth by having you bite down on some impression material, which hardens when exposed to heat (your mouth!) for a few minutes. Then, they create a mold from that, and they they create the mouthguard. They also send you your mold, incase you ever need to buy a new one.
I like it a lot! I can speak easier with it in. I can also drink water without having to take it out. Plus, look at that sweet skull I had put on the side, too!