Honest question, at what point does a workshop transition from ownable to not

If you also live in it, it becomes personal property - ie, ownable by you personally.

or in the outdoors of town among large factories?

I mean, that pretty much means it already is factory-like and no, it doesn't become ownable (unless you also live in it). If it involves other people's labor, then all the grey areas vanishes - it becomes communal.

The picture above is not completely accurate - a community might decide, for instance, that all firearms must be communally owned - ie, as in a communal arsenal (essentially a library for guns) - which, let's face it, would probably be necessary anywhere in the US (because it has more guns than people - and far less sense).