I have spent the last couple of weeks CAD'ing and adjusting a 3D-printable mount to attach a laser pointer to the FocusSpot port on a Kalart rangfinder as a focusing aid. The files, picture and some scale and finishing instructions are available at Thingiverse. The laser pointer is $1.50 at Dollarama in Cananda and $1.75 at Dollar Store in USA. From a quick look it seems these laser pointers are likely to work as well

Canada:

https://www.staples.ca/en/quartet-mini-keychain-laser-pointer-black-6447418061/product_100130_1-CA_1_20001


USA:

https://www.officedepot.com/a/products/783351/Quartet-Mini-Key-Chain-Laser-Pointer/

https://www.dollartree.com/2in-1-laser-pointer-key-chains/170246


If you have a laser pointer that does not fit, then you can keep the end of the adapter with the three tabs and redesign just the other end.