IKEA Lack table filament guide

This is my first design with Tinkercad. I needed something to fit the 38mm hole I drilled into my IKEA Lack table to feed the filament through. I wanted the hole to be a bit bigger to make it possible for the filament to move to the sides a bit when the z axis moves up. Both top an bottom edges are rounded from the inside.
I placed it upside down in my slicer and put some support between build plate and object and used a raft. I did not use supports inside which resulted in a not perfect round