This is a giant, one-of-a-kind zero-power illuminated finder that can double as an “Equalizer” for those of you needing an edge when participating in Messier Marathons. “What’s this . . . “ you’re asking? It began as a short-lived commercial product (name has been forgotten – anyone remember?) that appeared in ads in the back pages of Astronomy/Sky & Tel ten-plus years ago. It has a ~ 4” clear aperture and the finder body is heavy-gauge black plastic. Beyond its size, its unique feature is its ability to accept 4” laser-etched reticles that are illuminated by an internal, battery-powered red light source. The finder was supplied with a cross-hair style reticle for normal use, but the manufacturer made custom reticles to aid in finding virtually any DSO, asterism, double-star, variable star, etc. that a user wanted. These reticles were “made-to-order.” The original buyer of my finder ordered a set of ~110 custom reticles – one for each of the Messier Objects!
I have made a convenient storage archive for the reticle set using 3-ring plastic 8.5 X 11 protector sheets (intended for 5¼” floppy disks). The sheets fill two, 4” 3-ring binders. I modified the finder by enlarging the rear sight aperture to improve eye relief. I also fabricated an aluminum guidescope-type mounting ring system (with collimation screws) for installation and alignment of the finder. I enjoy this finder more as a curiosity than a truly useful accessory. It’s big, and if you know the night sky and can star-hop, you'll find Messier objects faster without the reticles than with them. Nevertheless, it’s an attention getter and fun to play with. Perhaps its just what you need for your ATM project.
It’s anyone’s guess what this is worth . . . I’d be satisfied with $175 plus shipping/insurance, but under the circumstances would also consider your astro-oddity in trade. PayPal or MO accepted, however buyer pays 3% fee if PayPal is used.