After finishing radiomatrix
, I found myself thinking that something much simpler might have wider appeal, not to mention being a lot cheaper. Allow me to present minimatrix:
Minimatrix is incredibly simple, especially compared to radiomatrix. It has just 8 parts in its BoM: A one-color 3cm LED matrix, an ATTiny2313/4313 to power and drive it, an 8-way resistor network, a battery holder, and two decoupling capacitors. Finally, it has a footprint for a thru-hole IR LED, making it possible to add interactivity easily and with little overhead. The IR LED footprint is situated on the back, so it can be placed then bent upwards to protrude above the matrix.
Here's the schematic:
This ought to be really cheap, and simple to assemble. I think we could do some fun things with this.