Vortex starts its life as an ancient cross symbol made from four circles whose centres lie on another circle of the same radius. Segments of the cross are then taken using concentric circles. Each segment is then shaped using a flattened circle lying perpendicular to the cross whose protrusion is controlled by another equation. Each part is then extracted, printed, painted and laid out. However the cross is twisted by rotating each concentric section.
From the front only one colour is visible, but from the sides each arm takes on a different colour or blend and the curves follow gradual arcs giving the image depth and shade. It works really well in a hallway allowing you to view it from many angles as you walk past.