You can print this without using supports and using 20% fill. It provides the same stiffness as a purchased adaptor and should pop straight into the lamp shade once printed.
Note : (nothing to do with the print). When fitting the light shade the screw on ‘nut’ of the fitting can be finger tip tight or even loose, do not over tighten it, or you will find you will not be able to remove the nut when you want to clean or replace your light shade in the future.
Printed with Yoyi PETG https://amzn.to/3UfIfMh
The author hasn't provided the model origin yet.