I created a red-dot finder mount for my QSI 540ws astronomical camera that uses one of the existing 1/4-20 mounting screws. The L-bracket shape allows the mount to attach squarely to the camera body. The mount exposes a dovetail compatible with Picatinny or Weaver rails. This allowed me to attach a a variety of small red-dot finders available for firearms.

The dimensions of the bracket are suitable for 500-series cameras with the WS sized front cap. If your camera has no filter wheel or has the filter-wheel/guide-port combination, you will need to remix to shorten or lengthen the bracket respectively.

I printed mine in Raptor PLA on a Monoprice Mini