Instructables has a neat if dangerous tutorial on how to quickly make a key copy by tracing the metal from a Coke can. It's pretty obvious, and with that seed planted in your mind, there's probably no need to read the instructions.
Let me go one step further and remind you that you can copy a key for like two bucks at the hardware store, and that combining scissors, a key, and the edge of a shiv of aluminium can, this tutorial might as well be titled "How to lose a finger." Also, entering someone's home with a key copy is probably still considered unlawful entry, regardless of the lack of shattered door frame. Having said that, I will try this later and let you know how it goes. [Instructables]