link to a laser, if you want to use a diferent one than feel free to do so, you just need to edit the bore inside a part called laser tube and everything should work fine:

https://allegro.pl/oferta/laser-wskaznik-laserowy-latarka-zabawka-kota-kotek-2w1-13319326091

instructional video on yt:
https://youtu.be/hzQJwwmpx4I

also, the 3 bolts are M5