iOptron RC8 (GSO) Secondary Mirror Collimation Mask

This is a simple secondary mirror mask I made to ease collimating the focuser with a laser. If you have trouble with it like I do this makes it quick and easy.
This is sized for the RC8 secondary baffle tube. I have supplied the FreeCAD design so you can adjust or remix as you need to fit what you have.
I printed this in PETG but will probably be fine with PLA etc. White is the best to see where the laser is.