23 mm to 30 mm microscope eyepiece adaptor

The stereo zoom microscope I recently bought came with 30 mm diameter eyepieces. I also bought another set of eyepieces but these were 23mm diameter.
So I designed the attached converter so that the 23 mm diameter eyepieces would fit in the microscope.
There will be shrinkage due to the nature of whatever filament is used - mine were made with ABS. The outer diameter fit the microscope well, the inner diameter had to be sand papered to fit. A cylindrical piece of sand paper works well to increase the inner diameter.The bonus is that sand papering made an exact snug fit on the 23mm diameter eyepieces.