Very nice outcome.
I tried to do a similar thing for my Optolong filter and my Canon 60D using 3D printing...
My problem was the shape of the filter (too big for clip-in design), so I ended with
different concept..
But.. this filter ring was clashing with focusing screen bracket inside 60D (I even lost the screen, it fell off, never to be found again so I had to buy another one... 450D was OK), so I ended with filter mounted inside the EOS adapter, using very thin retaining ring.
However, recently I found this filter doesn't help as much as it used to because LP (in Melbourne and Ballarat) is predominantly caused by LED illumination.