The following instruction is only useful for electrically talented people. No liability is assumed for damages resulting from this!
Some time ago I ordered some laser diodes from eBay. But since I only need one spare part, I thought about using the others as key fobs.
The existing wires are replaced by ø1mm enamelled copper wire. The 1.5 cm long wires are stripped at the ends 2 mm and 10 mm (with a file). After the soldering you should correct the focus by turning the front part of the laser diode (approx. 5m away from the wall) and fix it afterwards (solder brass housing).
After the assembly (see photos) I put a narrow cardboard strip behind the battery, before I fasten the key ring. Of course you have to pay attention to the polarity of the CR2032 (minus comes into contact with the resistor of the laser diode).
vy 73 es 55 de DH1ND
Layer height 0,2mm / 2 Shells