Last summer I acquired a big speaker cabinet from a 1960s Wurlitzer church organ. I removed the speakers and sold them leaving behind a motor that drove these big "flaps" that rotated in front of the speakers, which gave the sound a tremolo effect.
So, I put a red light inside and a fog machine. At night, with the red light, fog, and rotating flaps, it looks like something . . . well, different. I called it the "spirit cabinet."
Please watch the video of it in action.
https://www.youtube.com/watch?v=Kv0_eQxe7FU