Karamba 3D Stress Lines

Hi everyone.

I'm new to Karamba and I would like to make a structural analysis on a concrete panel (which is part of a shell structure). I'm interested in finding the principal stress lines through the solid of the panel.

I populated the geometry randomly of the panel as the source input for the stress lines. However, as can be seen in the picture below, the stress lines are only drawn on the surfaces of the mesh, not inside the volume.

I have several questions:

1) Is it possible to visualize 3D stress lines going through the solid?

2) Is populating the geometry randomly a good source input for the stress lines?

3) How would you find the (let's say four) most principal stress lines?

4) Is it possible to use a surface as a support instead of a node?

5) How would you easily extract a stress line with a slider?

Could anyone help me out please? Thank you.