A twisting cylinder. Play around with the sliders.
Inspired by the thumbnail of @leszpio's fascinating studio Geometric Solids QUADRICA: https://scratch.mit.edu/studios/30732303 It looks quite impressive despite the relatively simple math. It can be explained in three steps: ⬥ There are two ellipses made of dots. ⬥ The lower ellipse rotates. ⬥ A line is drawn from the bottom (rotating) dot to the corresponding top (fixed) dot.
