This is just a quick improvisation, I needed finderscope and RDF assembly so I put together existing parts to fit them on standard dovetail adapter..
Cost: $0.00, + 15 minutes of drilling holes in scrapped aluminium bits&pieces...
Attached is the model for 3-D printer... 1/2 only, two of them should be glued together (with acetone) and pic of final product.
Printing time: 6 hours (for both halves).