I’m still grappling with the electronics aspect of the water tank. The two switches are no longer a problem, but now the MP3 player stops all processing when the volume changes. I’m sure I’ll get past this one too: it’s just a matter of experimenting and probably more soldering and unsoldering.
In the meantime, here is the speaker enclosure for the water noise. I had originally planned to mount the speaker under the baseboard, but the more I thought about it, the more I wanted the noise to come from the right place. Besides, the water tank is mostly hollow, so there is plenty of space for a little speaker (8 Ohm, 0.2 Watt, 0.75″). Drawing the model to fit exactly into the available space took only a few minutes; I’d probably still be cutting and fitting if I had had to make the enclosure by hand!
Pembroke:87 