I designed this back when I was playing a fair bit of 40k. It's fun to use counters to represent hits from a Markerlight (like a laser target designator the Tau have), and I took the concept way too far with a marker that contains a little LED. Although I've got the parts and everything to make 5 of them, I only ever got around to making the one
Without further ado, here's some pics:
As you can see, I had to increase the height of the base by a couple of mm to fit the electronics and battery underneath. Ignore my dodgy styrene work - this was before my days as a famous scratchbuilder
The circuit design is pretty simple, but in order to maximise the life of the battery I designed a circuit with a tiny microcontroller (a PIC10F series for those in the know). Upon powerup the microcontroller flashes the LED in sequence three times every few seconds. It continues doing this for 5 minutes, after which it shuts down and enters sleep mode, drawing next to no power. It remains in sleep mode until it is woken up again by pressing the button.
Not much else to add but if you have any questions feel free to ask
