Has anyone used one of these specifically "Bahtinov Mask 3D Printed for Camera Lenses" Clip in like a lens cap

[Earl]

https://www.ebay.co.uk/itm/155285721776?var=455483654241

looks handy

Edited April 23 by Earl

[Celerondon]

Those do look interesting.  I have always 3D printed slide-on Bahtinov masks for my telescope OTAs but this is the first time that I’ve seen these clip-in masks.  I used the Bahtinov Mask Generator at the Astrojargon website and Fusion 360 (now Fusion) to create my mask designs.  Now I see that the online mask generator has been replaced with a standalone Windows program.

Don