There is a blue clear-plastic one, with a white lid and twist thing, that I was given a couple years ago. In profile it's rectangular, and from the top it's a sort of rounded rectangle or straight ellipse.
It's awful. The grind is random, the cup falls off, and the twist is designed so that when you grind the plastic catches your fingernail and rips it backward. If you see one of these, run -- don't walk -- away.