With their relatively narrow field of view, I always wished that my 20x80s has a finder. And, as it happened, I had a spare red-dot finder sitting around gathering dust. I wasn't able to figure out a way to attach the two until a member of our local group suggested using bulldog clips.
Here is my version of his invention. Drilling the spring steel of the clips requires a fancy drill bit. I found a titanium bit that did the job. The connecting bar is a piece of aluminum stock I had sitting around.