I found screwless model to hold power supply under desk (see link).
Unfortunately, the model doesn't work with my power supply and my desk. I remake model with OpenScad to fit with my power supply.
OpenSCAD file, allow to costumize holder to fit with your laptop power supply and your desk.
3 parameters are necessary :
2 gcode files are available (desk thickness = ¾ inch):
Enjoy it
The author remixed this model.