Invertible square (models become each other)

NOTE: These models are to be printed in vase mode with no bottom layers.

After playing with some invertible models, I wanted to better understand how to predict the resulting shape after inversion. A circle clearly inverts to itself, but the square inverts to something more interesting.

One natural question to ask is: If you 3D print the inverted 2D curve and then invert that, do you get the original curve back?

Although it is not true in general, for the square the answer turns out to be yes. There is something very satisfying about inverting a curvy print and having the lines come out straight.

These prints were done in PETG. When they are both in the same shape, the main way to tell them apart is which has more tension in it, and therefore isn't in its original printed shape.

This is a quick and easy print to explore these characteristics with. Please share any insights you have!

Other invertible models I have made.