This is a copying ring for the Festool OF 1010 router. I wanted to see if I can save those 10€ for the Festool one. Also I wanted one with 20mm outer diameter.Inner diameter 16mm, outer diameter 20mm.The part was designed in Solidworks. If I find the time I will make a parametric OpenSCAD version.Attention: Original Festool copying rings are made from metal, this one is plastic. If you use unauthorized accessories you do it atyour own risk!Print and attach to the router with the existing two M4 screws.Using the Skeinforge Comb plugin really proved useful to me. I printed at 0.5mm layer height which came out perfect.