Matlab assign geometry to materials

I desperatly try to run matlab script to simulate a 2d axissymmetric simulation.

The geometry objects and the materials were easily created. The problem is, that I struggle to assign the geometry to the materials.
Using the model.material('mat1').selection.set() seems intuitive, however I have no idea how I get the domain
information from the geometry objects.

Is there a simple way to assign the geometry to the materials?