I wanted a blue laser line for my tabletop strategy games so decided to build this thing. Its a really simple circuit and you will need some basic soldering skills to reproduce it.

Wire Shrinkwrap
(no link available)

Battery pack
https://www.amazon.com/dp/B09V7Z4MT7

Switch
https://www.amazon.com/dp/B0BXPFW69R

Blue Line Laser
https://www.amazon.com/dp/B0DJKPQG4Z

1. Remove the wires from the switch.
2. Cut the black wire to fit, add shrink wrap, and solder together. Then apply the shrink wrap.
3. Put the nut and rubber washer on the button.
4. Solder the red wires from the battery pack and laser to the switch.
5. Cut away part of the hole for the switch so you can feed the wires through.
6. Assemble. I had to drill out the screw holes a bit larger and used small 1/2 screws. Make sure you don't strip out the plastic.