The superellipse2d script is from 2013, and includes a squircle, I think as a subset.

https://moi3d.com/forum/index.php?webtag=MOI&msg=5616.1

About February 2022, a different squircle, using a different math formula, was created, the Fernandez-Guasti squircle. (Later in above link.)
This version is not a subset of superellipse2d. (?)

- Brian

I looked up the pronunciation of squircle. Combine the rodent squirrel with ircle.
(still hasn't made it into spellchecker :-)