A fine tip expo marker holder that slides onto a desk/table/shelf. The maximum thickness of the surface that it slides onto is 18 mm. Printed upside-down with the ring on the plate using supports. You can find this on Thingiverse at https://www.thingiverse.com/thing:6414155 and Printables at https://www.printables.com/model/694784-fine-tip-expo-marker-holder