I've extended my earlier parametric lamp shade to actually fit a nice old lamp where the cloche was broken.

In particular, the stand notch parameter allows the bottom to be inward rounded so it can be fixed with screws or "clicked" into something.

The parameters I've used are shown in the gallery.

I've put some more detail on how I made it into Instructions.
I've calculated this one with quality setting "2" (which took 100s on Chrome on a newer laptop).

Very high resolution now available.

Update:

For a long time now, the customizer has gone.
But now there's a new, better one.
..but it's missing this part and many more, and I need to prioritize.
Do you still need the lamp shade customizer? Please, head over to https://www.cherrykit.com/ and tell me if you'd like it resurrected..