[Otaku]

I put my Cow board inside the skull. Cut some small notches in the back of the skull to run the cables out. If it's too crowded in there with the battery pack, use a 5VDC regulated power supply to save space - just run in the cable.

 

[Otaku]

H71, I think what you need is a way to "dry trigger" the Cow board and then lock it out while the song plays. I don't know if the Cow board will initiate playback while it's trigger contacts are held shorted, or if it runs on a "make and break" trigger. If the former, a simple adjustable RC timer with a relay can be used. A 1M ohm pot can be used to set the time you need and prevent repeat triggers until the song is through playing. If the latter, you'll need a 2-stage timer - one timer to trigger a relay that starts the board, and another (adjustable) that locks out the circuit until the song finishes playing.
I have how-to's for both of these circuits - the RC timer version is triggered by a Quorum PIR directly, the 2-stage can be triggered by the PIR but will need a relay to prevent sending any voltage to the circuit. The Quorum PIR is on sale here:
SALE! Quorum A-160 Passive Infrared Detector-The Electronic Goldmine
Let me know if I can help.