Adam submitted his Open 7400 Logic competition entry, a 16 button keypad that outputs the hexadecimal value in a 4 bit binary equivalent.
Adam wrote
This is a handy device for prototyping, etc… It’s a hexadecimal keypad (0..9, A..F) that outputs the hexadecimal value on 4 digital binary lines (one nibble). It has both active high and active low output (so it’ll work for any system), as well as active high and active low strobe outputs for when the data is on the lines. I also added an on/off switch for convenience.
Via the forum.
This one actually looks useful!
Oh ya, I need a hex keypad like this :D