This will allow mounting a USB4000 Ocean Optics Spectrophotometer with a collimating lens to a standard Nikon camera microscope mount for simple florescent emission and transmission data collection.
Designed in OpenSCAD based on spec sheets at:
Print, attach spec with a bolt through the small home and mount in place of a camera. I didn't need to sand anything to get a light-tight fit. Print in a dark opaque plastic, or use a sharpie marker to prevent stray light if your microscope isn't in a darkroom. Note that you will have to adjust the camera focus tube to get maximum signal to the spec.
The other object in the picture is http://www.thingiverse.com/thing:33223