For the last three years I've been tinkering with these LED modules we have.
They're each about the size of a quarter, consist of one red and one green LED and four pins on the back.
You can see some of my progress here:
https://wiki.milwaukeemakerspace.org/projects/xmasblinkiesThe next logical step, if anyone is interested, would be to get some PCBs made and turn them into kits like the Learn-To-Solder Makerspace pins.
If you want one to make into a Christmas blinkie or whatever, feel free to help yourself to them or see me on Friday at the Holiday Make-A-Thon.