Case

[SteveB]

Leonard,
I am using a basic 16-key keypad, which can be bought surplus on the cheap (BG Micro, All Electronics Corp are a couple places that carry some).

Here is a link that has info on setting up a keypad matrix. The matrix size can be adjusted as required for your application:
http://www.rentron.com/serkey16.htm

Or do a google search (that's how I found the link).

Steve