EDIT: Just updated with a second file with the inside diameter 1/4 of a mm larger. I was having trouble getting the router, mount and shim to all fit together. Hopefully this will be enough slop to get it snug but easy to slide together. Your mileage may very depending on how well your printer is calibrated. The new file with the 69.25mm ID worked great for me. Printed using 0.43mm extrusion width.
This was designed to shim my Dewalt 611 router that is 69mm into the OpenBuilds router mount designed mainly for the Colt router that is 71mm.
I used a extrusion thickness of 0.5mm since this is 2mm wide for the main body. This way you should have a nice simple print without the printer trying to fill gaps. I printed mine with ABS.
For the file with 69.25mm Diameter I used a extrusion thickness of .43