This project attempts to use simple, common components that I suspect most people already are in possession of, and are familiar with. The circuit consists of the most basic building blocks in musical synthesis, namely an oscillator section (driven by the CD40106), a VCA and envelope generator section (both using the LM324 single-supply op-amp), and an amplifier (LM386) that goes to the speakers. Basically, it's the same thing done four times, where the oscillators are tuned slightly different for each iteration. The whole thing runs off of +12 volts. I made my own power supply with a transformer because I like to keep things as an entity rather than having a potentially noisy and ugly external one. I will not include the power supply in the schematics, however. If you have the knowledge to make power supplies you can probably cook one up yourself, but if you do not, you should stay away from it and rather use an external one.
I sort of ad-libbed the structure of the sculpture, and thus it ended up a bit more chaotic-looking than what I had imagined. If you wish to use this circuit for your own sculpture, there's no one stopping you from making your very own structure, however. The wire I use for the frame is 14 AWG bus bar wire from Alpha, which I bought from Farnell. Underneath you can see the basic framing for the sculpture.
There are some variables to the circuit, and you may need to figure out what's best for your set of speakers. I had two pairs of 1 W and 1/4 W speakers laying around, so I needed to compensate for the lower volume from the 1/4 W speakers. This is reflected in the "optional" part in the schematic.
Keep in mind that what you see on my breadboard is the schematic times two. As mentioned earlier, you might want to put different resistor values (all in the megaohm range) for the gates triggering the envelope generator.
When the breadboarding and fine tuning is done, you can start building the various modules inside squares of 6x6 cm. The wire I used for the squares is an 18 AWG bus bar wire, also from Alpha.
When that is done, you just solder these squares to the frame and connect the loose ends and you are finished! Remember to double check everything before you commit to something. It's easier to fix early in the process. Good luck!