A one-night hack, I made this after becoming frustrated with procrastination. The brains is an ATtiny85, with a few normal LEDs and one RGB led charlieplexed together to show different colours, and a button as the user input. Press the button once to get it going, and it will show green, yellow and then red LED's for five minutes each. Then, when time is up, the head flashes through some different colours until you push the button to turn it off. The whole thing runs of a coin cell or can be plugged in to a computer, and it was a fun test of soldering since I chose to use SMD resistors and do everything free-form to be embedded in the plastic. Speaking of which, the body is made from my new favourite material - PolyCaproLactone (PCL). You melt it in boiling water and mould it like play-dough and it sets to a hard white plastic with great LED diffusing properties and a nice smooth texture.
So this project was partly inspired by me getting my hands on a very useful material. I made a video, which includes me showing off the titular substance and my little octopus pal. I'll get round to posting code and a schematic in the next few days (hopefully motivated my the octopus!) but for now here's the vid (skip to 4 mins in for the good bit):