Hacker News Reader

Hinge on one side. Piano hinges on the parts that fold. Math to calculate the correct angles. Didn't seem like voodoo to me.

This is the one that really looks like magic. https://www.youtube.com/watch?v=10y28PD73vk

How the table is made. The details are beautiful. https://www.youtube.com/watch?v=uVbo7ycpkeI

That one probably has tracks inside that move each piece through its path as the table rotates.