Summary This is an OpenSCAD design of a ring to hold samples for light soaking in a solar simulator. Print and attach sample with binder clips and hold with chemistry clamp as in photo. 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