Summary

This is a one-size fits none holder for standard 2" x 4-1/4" (50.8mm x 108mm) magnifying lens or shade lens used by welders. Obviously, you shouldn't use it for welding but it might be useful as self made PPE for removing FDM supports, painting mini-figs, etc. With a reputably made shade 14 lens you could also view eclipses. Adding some foam to the nose piece and brow would probably make if more comfortable.

I printed with a 0.8mm nozzle at 0.6mm layer height with 2 shells and 10% infill. Simplify 3D had trouble with the model unless oriented with the top to the build plate so be sure to check the slice preview carefully. I think this is because Fusion 360 is confused about some edges. It will need supports but watch for supports merging into the slots as they will be hard to remove. I didn't check them carefully and had merging on one side that took a while to remove.

Thingiverse doesn't seem to like the STL either as it wont generate a preview.

10/13/23 I added the retainer. This should help keep lenses in place.