My kids broke one of the old shades (background) and it had been discontinued, so I tried to create a new one in roughly the same shape that was a better match than the brown replacements we had to go with. I'm not happy with how stripy this filament came out but thought I'd post the model in case it works for anyone else.

Works fine in translucent PLA as long as your bulb is LED or possibly CFL. I wouldn't try using this with an incandescent bulb. Translucent PETG would probably be better if you can find a color you like. Print with the flat part on the bed and no supports needed. Use enough perimeters to avoid infill for best appearance.

Update:
I made a vase mode version that uses much less filament so it transitions colors much more slowly and lets a lot more light through. I modified the top a bit to remove the radius and allow better bed adhesion when only 1 wall layer used. You will need to print several bottom layers (which will be at the top of the printed shade) to have enough strength for the threaded washer to hold onto the fixture- five 0.2mm thick layers or 1mm total was fine for me. Shown in pics #3 & 4.