Are there documented rules for creating/joining geometry via ruby script?

Unfortunately, no.

The YARD documentation generator allows for these kind of tutorial files to be added. But only a few have been written so far.

The API dictionary of classes and methods are terse and not meant to be a teaching document. (Ie, it’s an API reference, not a programmer’s handbook.)

There is talk of working on the files repo. It’d be hosted on GitHub in the SketchUp Team’s repositories.

It came up recently in this thread …

… which prompted this specific topic to be opened …

:bulb: