EscherTrefoil

the 4-d model @ 45°

And finally in terms of a comparable shape to the last two prior patterns combined, we see the trefoil, or three-fold knot. This is the result of taking a "tube-torus" and adding an extra dimension of motion or spin to it. Then, instead of only clock-wise or counter-clockwise, there will be an additional direction for spin or rotation. Here we see the shortest distance between any two points on this model may be a straight-line only if it does not follow along the surface of the model, but instead breaks the surface to travel outside the model entirely.