Christmas Tree OrnamentNot a keyboard, but made with many of the same parts. Other than the LEDs and PCB, the rest of the parts I already had.
The PCBs were made a while ago but I only finished assembling it this weekend. The first PCB version had sharp corners and was too dangerous to put on a tree. I rounded the corners and had another set of PCBs made. These are under 100x100mm and can be made at most places at a discount.
I used self flashing LEDs. I ordered some 5mm green/red flashing LEDs on eBay. They were supposed to be diffused (milky white), but they sent clear LEDs. These are way too bright and directional. The replacements they sent were also clear. So I ordered some 5mm RGB diffused flashing LEDs from another seller. The green/red does look more like Christmas tree lights.
There are holes for M2 spacers. Some are too close to the resistors to fit. But there are enough to hold two PCBs together securely. The board is powered from a mini USB connector.
Files on github.
First version on the left, rounded corner version on the right.
The bare PCBs. You can see how sharp the corners were on the original PCB.
I used 1/4 watt resistors on the first one. They fit but the LEDs would not fit in some spots, I had to grind a bit off the edges. The 1/8 watt resistors on the second one don't interfered with the 5mm LEDs.