It's been quite some time, working on this off-and-on. But the (hopefully) final prototype board just arrived. It's a 12-inch wall-clock with three rings of 60 LED's. I'm hoping to offer it as an assembled, working clock, as well as in kit form. And, yes, it will be open source.
[EDIT] Forgot to mention it also has a 6-digit, 7-segment digital readout in the center for times when you don't feel like translating the rings to time. The center readout can be toggled on/off. It also has three different display modes: Progressive fill-up, fill-down and "classic" (only one LED active per unit of time). In case it isn't obvious, the outer ring (red) is seconds, middle (green) is minutes and inner (blue) is hours. It's been a fun project, full of learning. Inspiration to go for it comes from places like this forum, and guys like Dave and Ben Heck on YouTube.