Do you use one of those fancy Kryptonite bike locks? If so, I have a tip for you. If you ever lose your key, just whip out a bic pen and you can pick it in about 5 seconds. Video here and it works with other kinds of locks too.
I should also note this is the kind of lock used on many laptops as well.
I knew there was a tricking using fiberglass resin and WD-40 to kludge a key. (great for company coke machines if you hate your boss) I never really thought about applying it to existing plastics.