I'm a big fan of the Optivisor from Donegan. https://doneganoptical.com/product/optivisor/ For the amount of time I spend looking at small stuff, it's worth it to get the genuine article rather than one of the million cheaper options.

I didn't like the options for a light source though... or at least I was scared off by the reviews... and isn't that why we even have 3d printers?

NEBO makes the Einstein Cap headlamp https://nebo.acgbrands.com/en_US/einstein-rechargeable-cap-light.html that gave me the excuse to over-complicate this project. It has a “motion activate” mode so you can just waive your hand in front to turn it on and off. That's what those little round LED's are on either side of the actual light. The problem was that the activation zone is well-inside the working area of a mag visor. The “wings” on the font of my contraption reflect the IR beam up and over, so just swiping your finger above the light will turn it on and off. Use little squares of shiny aluminum tape for reflectors.

You have to flip the clip around. The pin that holds it in place has a large end and a small end. Press the small end of the pin to remove it. Pay attention to which piece the larger, splined end comes out of. After flipping the clip around, you'll want that spline pressing into the same spot.

The part that screws onto the visor has ridges that mate with the ridges inside the NEBO clip and keep it firmly in place. It will not interfere with the headband. If you don't want to mess with the motion activation, this is probably the only piece you need.

I had the best luck (and least support) with the “back” open end on the build plate.

I've provided two versions. One with the buttons as part of the model, but you'll need extra supports and you may lose some resolution on the buttons. The other version has the buttons separated to be printed in a more favorable orientation, and also has some “integral support material” around the button levers. The idea is that you carefully snip those tabs out before use.

Designed in FreeCAD.  Thank you FreeCAD developers and forum members, and thank you Mango Jelly for your AWESOME youtube tutorials.  I couldn't have done this without you guys.