I've designed a set of diffusers to work with these clip on desk lamps off amazon (Xtricity Desk Lamp on Amazon). Outer diameter of lamp was ~109mm. You should be able to scale the XY to fit other sizes. Z of diffuser face is ~.3-.4mm. This seemed to be an ideal thickness for light diffusion. There is a simple round version, and a larger "lightbox" square version. Both seem to work quite well. I use them to light up my standing desk when I teach Zoom classes from it. Printed with white Hatchbox PETG on a Mini+
Print flat side down. No supports should needed on either.
Update (12/24/21): Added the fusion 360 file so folks can resize to fit other lamps.
The author hasn't provided the model origin yet.