This is a chopper wheel for optical and optoelectronic experiments.
This is a customizable chopper wheel -- derived from the very nice ---Parametric encoder wheels and the shaft lock for wheels with a nut cage for mounting firmly to a spinning shaft from our less versatile Parametric open-source chopper wheel. It is a bit rough, could be made even more flexible and the OpenSCAD could used cleaned up a bit, but I leave that up to you.
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. Click the reference links to read more.