This is a lens holder for optical experiments.
This component is part of the Open-source optics project, whose goal is to radically reduce the cost of scientific optical hardware: by the Michigan Tech's Open Sustainability Technology Research Group.
All measurements in mm. Scale for your application and print on your favorite open-source 3-D printer and enjoy. This component is part of the Open-source Optics Library: Zhang C, Anzalone NC, Faria RP, Pearce JM (2013) Open-Source 3D-Printable Optics Equipment. PLoS ONE 8(3): e59840. This is part of a larger project to reduce the cost of scientific equipment using open-source hardware.
Read more about the project in the reference links.