This is a reverse alignment tool for Co2 laser machines from Omtech.

I upload this upon request, but I really encourage that if you can afford to, that you purchase the “real” tool from American Photonics, it even comes calibrated!

Please note that you need to make sure to print this in very high tolerance.
The outer diameter needs to be 16.25 +/-0.01 mm
If smaller it will be able to wobble in the laser head, giving bad precision.
If larger you may not be able to mount it in the laser head.

You may also need to enlarge the upper diameter where it holds the bore sighter in place depending on the tolerance on your printer, it needs to be a tight fit!

The three holes are dimensioned so that they can be threaded for M4 screws of equivalent.

The model is made to be printed with 0.6, 0.4 or 0.3 mm nozzle.
You'll need to print it slow at ~30mm/s and 0.2 mm layers to get a good part.
 

The amount of shrinkage of the plastic you use play a huge role on the final diameter so you might find that you have to scale up the model in your slicer so that the printed model get accurate dimension. 
(Took me 8 tries myself of as the plastic to get it to proper final dimension of 16.25 mm)

Here is the cheap bore sighter I used for this project: [https://www.banggood.com/custlink/D3vRkgSJSm](https://www.banggood.com/custlink/D3vRkgSJSm)

And here is a little video I made of the project: