Thanks @arjanus for the nice build. I took the drawing and modified it a little so a change of the major diameter in the highest level sketch will cascade changes down the drawing so it all updates and keeps things nice. Tested between 28 and 32mm. Only print tested at 32mm with a very nice snug fit- the dowel makes a nice pop when it goes into place.

To use, download the assembly and part file. Change the 'Rod Diameter' dimension to that of your dowel rod. Rebuild the drawing. Save the assembly as your stl output.

If you dont have solidworks to make the needed changes, post comments here and I or someone in the community will upload a STL pack.