in fact number pads DO exist for mp3's about once amonth we install one into the sound booth of the new buildings we do in NH and VT. its an incredibly simple device that just has a number pad a green go button and a red stop button. it has an LCD and programing for only three songs. with a 2 gig card it holds all the k songs and the melidoys too. very nice device... but impossible to find. but they are out there. i will give you more info if you want.
My son is looking at an eagle scout project for a local nature center, he would like people to be able to select animal sounds from a kiosk where they could enter the animal number on a key pad and it would play the animal sound and an interesting aspect. How could he set that up? What would it cost? Where would he get the materials.