import solids; size(200); currentprojection=orthographic(5,4,2); revolution upcone=cone(-Z,1,1); revolution downcone=cone(Z,1,-1); draw(surface(upcone),green); draw(surface(downcone),green); draw(upcone,5,blue,longitudinalpen=nullpen); draw(downcone,5,blue,longitudinalpen=nullpen); revolution cone=shift(2Y-2X)*cone(1,1); draw(surface(cone),green); draw(cone,5,blue);