Improved Design

This design makes the center rib taller and thicker, and adds a rib all around the rim to prevent any mishaps there with the eyepiece holders. Instead of the clips. this uses three machine screws and nuts per joint ($1 at Walmart) utilizing the thickness of the clip in the part itself. Rather than the one-piece center hole, each part has its own rib, and the perimeter rib attaches to the center around the 2" slot.

I ran out of red glow-in-the-dark material after the first print, and no one has any more of it, so I switched to some orange material I had. It printed ok, but was pulling up the tape at the edges, so there's some small amount of curvature.