A simple lampshade I designed and printed using "spiral vase mode" or "spiralize outer contour" as it is known in Cura. Make sure to disable top and bottom layers and ad some brim if you feel that it is necessary.
The hole in the centre of the mounting piece is 28 mm in diameter. I am not sure if it is a standard that fits any other lamps than the one I have. But even if it does not fit, you can still use my design as inspiration and create something similar. The lampshade itself is 14 cm high and 10 cm in diameter.
Skip to the end of the video for the result.
Added another version of the lampshade with a more rounded shape.