From Trammell Hudson's Projects
For 2015's Burning Man, we've designed a much simpler Blinky Hospital pendant. This one uses a CR2023 battery and only two layers of acrylic and is much less complicated to build compared to last year's design.
As with all Laser cutter projects, there was quite a bit of experimentation to make it work.
Cut the Outline and Logo layer out of clear or colored 3mm acrylic. Be sure to etch fairly deeply; I used 40% speed at 100% power. Then cut the Outline and Battery layers out of mirrored acrylic. The colored acrylic flipped so that the etching is inside.
Bend the leads on a slow flash 5mm LED to make a bump that connects to the positive and is secured in the notch. The negative lead is cut short and runs along the etched groove of the LED in the logo.
I found that a clear 3mm top looks better than colored acrylic since the LED cycles through so many colors. The best back that I've found is normal mirrored 3mm.