Living Hinge Design GUide

[curious aardvark]

I guess I'm just going to have to prove this :-)
And I presume you're totally disallowing flexible filaments ?

Given that polyflex will print stiff parts as well as totally flexible parts and is damn near indestructible. Printed some 0.4mm sheet a while back - could not tear it.
That's proved the point right there.

But there are other materials that will also do the job.