The filter is held in TPU threaded part and TPU washer. This part can be screwed into a holder that is put on a telescope. In my case, I put it on FRA400 scope. Holder part can be designed for any scope. All other parts are printed with PETG.
There is also a dustproof cap for the filter
And a flat panel cap
I've used m3 heat inserts with nylon bolts
The project is insipred by https://www.thingiverse.com/thing:5483995 fitting my needs