He had called wednesday, and I had talked to him about the things I am designing at the moment. I know that he likes to receive things I make for him as a gift -- there is the four-panel moodlight and the binary LED clock with cheat-button, but his birthday and Sinterklaas are coming up, so it's time to once again start cracking!
He liked the idea of the randomised LED rail -- except we will need to make it in a more compact housing (my mom would go crazy if we'd do this on top of the bookcase). That's not too hard, we'll just make it a spiral with right angles. But then he also said that he wants the individual lights to have different colors. Which would mean that I'd have to drive RGB LEDs, which drastically increases pin counts and cost...!
I have to mull this over and do some calculations, to see if I can visualise how that would have to work. Charlieplexing would be much, much more complex because of the common cathodes of the LEDs, and with the increased pin count comes increased complexity.