Curtain Rail Sliders

My perhaps a tad too cheap Curtain rails have sharp metal corners that chew through the original plastic sliders. Instead of hunting for the right ones in Hardwareshops, I thought I rather spend some time, coming up with a model on FreeCAD that I can print out as I need them. I added the FreeCAD file, so it's easier to change things a wee bit. To change, delete the last step, the Fillet step those are particularly unhappy when you change things further up…