Here’s a great example of how to make a Christmas pipe organ. You can also check out ethernet-controlled color organ I made couple years back.
A homemade choir organ and pedalboard with a compass of one chromatic octave (C 4′ to 2′). Built during Christmas break, this organ first became remotely playable on Christmas morning, 2008; it formally debuted that night when it was used to accompany Christmas carols. (And two months later, I finally succeeded in getting both audio and video on to my computer.)