My original design Solar Eclipse Finder Scope. I sell these on eBay and Etsy

I’m planning to view the April 8, 2024 Solar Eclipse in totality and plan to bring a couple telescopes with me. One telescope will be set up with a filter to view the sun through the eyepiece, and another will be projecting the solar image a few feet away to create an image of the sun that’s about 16″ diameter so that all of us can monitor the progress of the eclipse before totality.

It quickly became clear that aligning a scope to the sun, without looking at the sun, was harder than expected. I tried the shadow method and got it to work eventually, but I wanted a much faster and easier way to do it. I searched around for a solar filter for my finder scope, or a special solar finder scope and found some commercial products in the $50+ range, but I didn’t really want to spend that much, especially since I was outfitting (at least) 2 scopes. This sounds like a job for 3D printing!

I took a look at my favorite finder, a Tel-Rad, and decided I wanted my 3D printed finder scope to be just as easy to use as that. I went through a couple of iterations, but finally came up with a nice finder scope that is super fast to use, lightweight, and looks really nice, too!

If you’re interested in purchasing one, I sell these on eBay and Etsy

I decided to print these in tough, durable PETG so that it would be more temperature resistant than the standard PLA. I printed a super thin, translucent screen on the bullseye finder so the sun lights through it. You can see the bullseye pattern from both sides, as well as the illuminated area.

The finder scope mounts to a dovetail, and is adjustable side to side and up/down. I designed it so it ships flat and assembles easily with 4 stainless steel machine screws. Based on requests, I print this in both black and white bodies. This is one of my favorite designs for a 3D printed part yet!