Summary This is a chopper wheel for optical and optoelectronic 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]( http://www.mse.mtu.edu/MOST). For similar see the Open-Source Lab How to Build Your Own Hardware and Reduce Research Costs Instructions Use the OpenSCAD files to customize it for your application, print on your favorite open source 3-D printer and enjoy. It is only one number that controls the number of slots. 4, 10 and 14 slot stl files are shown as examples and should cover from low frequency to about 1400 Hz. You can of course go higher if you need to. Included are the code for wheels with a nut cage for mounting firmly to a spinning shaft. Full information here on Appropedia Thanks to Nick for the code. 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 here