Clipping Plane Transparency Mode Setting View inside STL Model

I am trying to use the CLIPPING PLANE to view the interior of my .STL 3D MODELS in a cutaway view but as soon as I letgo of mouse left button it hides the view with a solid fill.
Where exactly can I find the settings for transparency so I can actually see and render these cutaway views?

Hi TavVal -

By default, when the section through an object creates a closed curve, the clipping plane will produce a solid fill. You can turn that behavior off either for all objects on all layers by changing the display mode or by turning it off for individual objects or layers.

Display mode: Go to Rhino Options -> View -> Display Modes -> [Your_Mode] -> Objects -> Clipping Planes and uncheck both “Use section styles” and “Show fills”.

Object or layer property: Go to the section style and uncheck “Section open objects”.

For each of these workflows, you can also assign a semi-transparent color if you don’t want the section to be completely open.
-wim