Tom's sound system is a Sparkfun MP3Trigger and a Sure 2x2 AMP. Both of these components have a small enough footprint to store inside the Money Lover's Barrel that makes up his torso.
My sister had a Christmas request, she wanted Tom Servo from Mystery Science Theater 3000.
Good luck! He's a very rewarding build even if you don't do the electronics. This Tom sings an upbeat version of the funeral march. I don't think I want to see 6+ of them singing that.