Actually, I've had good luck tracing around favorite diapers (stretching out the elastic) and then adjusted as I saw fit to make my own pattern.
I started with the HoneyBoy pattern, though, and I found that a great place to start. You can order it at SewShoppe
. They have other patterns, too. I guess I'm a pattern person...I like to start out with one, and then monkey with it to get exactly what I want.