It's not that hard to build a CD player, actually.
All you need is the following:
- a laser
- a few integrated circuits
- resistors
- capacitors
- solder
- a rat
- a rat wheel attached to a CD spindle
- an ample supply of "processed cheese food" used as an award when the rat runs at the correct speed (that stuff will last for years before it rots -- the amount you use depends on how much you are planning to use the CD player.)
- and of course, an electric shock mechanism to punish the rat for running too fast or too slow.