Hey 3dfan,
Brian (Bemfarmer) makes these types of scripts

He has a Hypocycloid script and a couple others. THey are setup or "geared" towards making gears (I made a funny there)

But the math should be there!

I used his epitrochoid script and entered a negative number to generate this result... I "LOOKS" like the astroid, but I am not sophisticated enough to know whether it truly is one or not.

With this info, either he can come in and confirm which script to use or maybe modify a bit an existing one



Maybe some discussion on the values in his hycycloid script to generate the astroid...

Anyway, thats the best I got