OK I solved this one.
I must say though that on the manual it could be explained better.
Just give a rigidbody to the main mesh, but NO collision primitives.
Then, add a GameObject to the mesh and a collider to it but NO rigidbody!
And you can add as many GameObjects/colliders as you want for that single mesh.
This way collision primitives are also much quicker to edit because you can select the collision primitive and move/rotate/scale it as you wish using the widget instead than use numerical input.
317779–11212–$watswrong_145.unitypackage (33.3 KB)
Also I placed a hing joint between 2 objects and they are linked OK but the smallest one is “floating” around, and getting back to its original place but not quite FIX in its hinge place. Why?
Edit: also this solved.
It depends on the mass of the linked objects.
Another question: is it possible to disable bodies collision inside a tree of objects? In other words, if I have an object that is physically connected with hinges and some of its bodies are crossing each other, is it possible to disable their collision only between themselves?
You can use Physics.IgnoreCollision to disable collisions between any two colliders.