a cone that represents three conic sections, circle, parabola, and ellipse (the ellipse is only half an ellipse) if you print out one, you have these three conic sections, but if you print out two, you get these three (with a full ellipse) and a hyperbola, another conic section.

print one for a parabola, circle, and half an ellipse. print two for a parabola, circle, a full ellipse, and a hyperbola! print with supports.