Our code has four different modes, one for each of the four seasons, plus a mode for "off". We've hooked up five capacitive touch pads on the Circuit Playground Express to trigger the different modes. We can leave it like this and mount the Circuit Playground on the outside of the tree, or we can get a little fancy and make a custom controller using metal buttons or copper tape, or really anything that conducts electricity. Check out this fruit sequencer for inspiration!
Craft stores sell a lot of charms or jewelry findings that will often work well. Use a file to scrape off any top coating so you're touching bare metal, and solder a wire to the back of the charm.
I went one step further and made cast pewter "icons," embedding the end of a wire in the molten pewter before it set up. This connection is really solid and steady, so I really don't get any misfires and there's no chance of the solder connection failing.
The details are beyond the scope of this (already complicated enough) guide, but I'll go over the basics because it was a fun bit of silliness to create.
First, I made some little icons out of polymer clay: a flower blossom for spring, a leaf for summer, an acorn for autumn, and a moon for "off".
I pressed some kinetic sand in a metal tray and made an impression of each icon. Then I melted a pewter ingot in my crucible and poured some pewter into the impression. While the pewter was still molten, I inserted a wire (with the shielding removed) to connect to the Circuit Playground, and also a u-shaped bit of galvanized wire to use as an attachment point to the tree.
The kinetic sand is not great at capturing fine details, but since my icons were simple shapes that didn't matter too much. I polished them up with the sanding bit on my Dremel, and they came out shiny and lovely!
Some of them took a couple tries to get right. The nice thing about pewter is that it's pretty waste-free -- if you don't get it right, you can just melt it down and try again.
I have a removable access hatch on my tree, so I mounted the buttons there. I drilled a small hole for the wire to poke through, and used the galvanized wire points and some E6000 glue to help secure the buttons to the bark.
I attached the four seasons buttons to a male 4-pin connector, and the moon pin to a 2-pin connector, for easy attaching to the Circuit Playground Express. Now I can change modes just by brushing my fingertips over one of the four season icons.
Sleeping under the tree is such a delight. This project was a lot of work, but the results are simply stunning and 100% worth the effort. There's a fairyland in my guest room. Who wants to come visit?