Just use a freeware CAD program. Set the page properties to the same as your panel. Then set the dimensions to inches (I don't do metric). Create your objects, which can be as easy as squares for joysticks and circles for buttons/trackballs - basing your sizes on specs from the vendors. I'm using Solid Edge 2d drafting, which is freeware.
If you have the access, you could also send the file (exported probably as PDF) to a printer who has a large format printer, and voila, you have a true to scale printed template you could just tape to your panel! I was going to do that for my cabinet, but instead just cut out stuff based on dimensions. Probably should have though, hard to figure angles by hand (but the program will do it for you)...
- Kirk