Purpose
This box only has a value for Nurbs surfaces and Polygon sets;
otherwise it is empty.
If the current solid is a Nurbs surface or a Polygon set, then
the value toggles between 'solid' (completely filled with material)
and 'hollow' (material only exists within a thin shell).
Usage
Click on the solid/hollow box to
toggle between solid or hollow mode.
Comments
Some Nurbs objects that have this value set to 'solid' will be
rendered with flat cut-off planes (i.e. a cylinder will have
end planes).
For polygon sets you can also use the
equivalent input box in the edit poly sub-menu.
