I was snooping around the net and came here:

http://www.shapemagic.com/index.htm

In the Freeware section I found:

Shape Magic (it requires Quick Time, for the Hyperstudio it uses). For object creation, it sounds like modelling with a mechano set (but I only skimmed the surface).

Road Maker, for terrains.

In the Download section, there is more content for download, like a pair of earings for Posette.

Thanks for your head up Amish.
Seems to be interesting for some kind of "Extended primitives"
I'd give it a try, but QuickTime is NoGo for me
It's an old program, and at first glance other free modelers seem more powerful (Blender, Wings, and even Anim8or...)
But maybe I'm wrong...

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I'm not so keen on putting on QT, myself just for this, but I think the Road Maker does without the Hyperstudio. I shall need to re-read and make sure before I install it.

There are better modellers out there, as you say.