Not terribly complicated or beautiful pieces, but they’ll come in very handy when I view next month’s total solar eclipse. I found the commercial versions of these hard to find in all the sizes I needed and/or were prohibitively expensive.
I’ve now cut small ones for binoculars, a medium for a camera lens, and a large one for my 8" schmidt-cassegrain telescope. Designed in Fusion 360 and cut from 3/4" baltic birch, and all but the smallest ones use a separately cut inner locking ring to hold the filter film in place. Blind nuts with nylon thumb screws allow these to be secured in place so they can’t fall off and set your eyeballs on fire!
The 8" set was my first model and is a little rough since I had to manually rework it, as the original fit on the 'scope was too tight and the locking ring clearance wasn’t sufficient. Now that I’ve had some practice, I may recut this one from an attractive hard wood and finish it.
Filter material was obtained in sheets made by Thousand Oaks Optical specifically for solar viewing. Just in case you were going to lecture about the dangers of staring at the sun through who-knows-what darkish mystery material.