Cranial Discharge

Giant Music Box

Build a large music box type of machine – maybe a 55 gallon drum with spikes of some sort that is turned via a geared crank mechanism. Large tines made out of metal strips would produce tones as the spikes hit them.

The trick is to make it so the music can be changed as needed. The drum would have holes drilled all over it, and the spikes can be plugged into any of the holes. That way moving the spikes results in a different piece of music being played as the drum is turned.

Issues: spacing the holes so that even notes (8th and 16th notes) and odd groupings (at least triplets) can be played.

Large Color Clock

A large clock that shows time by two or three large, overlapping color wheels. Each wheel is some sort of gradient with a line showing the start and end of each gradient. Those lines are the hour, minute and second hands. The wheels are at least somewhat transparent so the colors are constantly changing.

I think it would be easy to build since clock parts are easy to get. A strong enough motor would be required, and the material for the wheels has to be light weight.