Thanks to int2str for making the original that this one model is derived from. I used SpaceClaim to create another model that has a 50mm wide LED strip guide with an extended grip which goes to the full width of the extrusion. There is a 2 degree slant on the grasps to help it hold a position on the extrusion. Also there is a small hole on one grasp for a set screw should you need it. The best fit has been a M5 but it may also work with a M3 socket cap.

Attribution - Creative Commons

LED, Light, Mount, Orion, Rostock, SeeMeCNC