Get out your powdered graphite. This stuff is extremely messy and not good to breathe, so wear a particle mask and gloves! (I promise I went and put on gloves right after taking these first two photos.. what a mess. It cleans up easily with soap and water though). 

Mix the graphite into your clay. Use a LOT. Add some water if it starts to feel too dry. Keep mixing until the clay is black through and through. You need a solid, unbroken chain of graphite atoms, and the best way to be sure you've got that is if you can't see any white clay at all. Pack as much graphite as you can into that clay.

I sculpted some of my bottle toppers entirely from graphite-impregnated clay. For others, I rolled out the clay and wrapped it around an object -- a small bottle, a shell, or a ball of aluminum foil. 

The clay in this photo does not have enough graphite. When this bottle topper dried, the capacitive touch stopped working. That's very sad!

To fix this, I made a slurry of graphite and water, mixed together until it was a paintable consistency. I applied this over the top of the clay to achieve that unbroken graphite atom-chain, so that anywhere I touch on this sculpture will set off the capacitive touch pad.

To carry the capacitive touch signal to the Circuit Playground we'll need to embed our long wire into the wet clay. Strip a few inches of wire and wrap it around your topper to achieve maximum electrical connection. Embedding the wire in a ball of wet graphite clay and pressing it onto your sculpture works well. Make sure there's a lot of contact between the wire and the graphite.

You can hide the wires inside the bottle decorations or just let them run down the backs of the bottles.

Once the clay and graphite slurry are completely dry, mask your bottle - aluminum foil works great for this - and paint the toppers. Metallic paint will not block the capacitive touch powers of your sculpture as long as you keep it to a thin coat. I had success with both spray paint and metallic acrylic paint. I didn't try a non-metallic color, so I don't know whether the metal in the paint helps with the conductivity or not (or whether this paint even has real metal?). I experimented and used what worked! Feel free to do the same. It's your castle.

My octopus sculptures worked for days, then finally dried out to the point that they stopped working. Instead of starting over, I added a copper tape sticker to the tops of their heads with a line of copper tape attached that wraps around the wire. Copper tape is very conductive, and will not disappoint me by drying out. 

It's not cheating to add copper tape if you're having trouble!

Once you're sure your toppers are rock-solid conductors, place the bottles onto your base and thread the wires through the holes. I found it helpful to place the base up on blocks to give myself room to work underneath.

Solder the wires into the holes on the MPR121. Here's how they're laid out in the code we've provided:

• Pin 0: not used
• Pins 1-8: Tone-playing bottles, from low to high
• Pin 9: Octave-shifting bottle
• Pin 10: Off switch bottle
• Pin 11: Demo mode bottle

Once everything is working, glue the bottles down to the acrylic base with strong glue. I used E6000. 2-part epoxy would work as well. Make sure they're solid, since they'll get tapped and touched a lot and you don't want them falling over.