I like the shape of hyperboloid cooling towers so I made this one as a pen cup. The dimensions are scaled down 1:1000 from the award-winning† Didcot B Power Station. 

In real life, the design is used because the hyperboloid is structurally strong and also enhances the chimney effect which pulls air through the tower. 

The design is sturdy with 3-layer thick walls and the wide base keeps it from tipping over. No supports are needed as the filament bridges nicely above the air inlet section.

†Voted Britain's 3rd worst eyesore by readers of Country Life magazine. I never said it was the good kind of award.