Echo/reverb/flanger/chorus built from a circuit bent karaoke boombox. Added electronics include an input buffer, LFO and a mixer. The speaker outputs are used to drive a spring reverb tank. Built into an old aluminum mailbox.
Totally homemade spring reverb - LM386 amplifier circuit, "exciter" speaker/driver thing, and piezos soldered directly to the springs. Stereo spring reverb.