Checking Faceted Body Thickness

Select the Thickness tool.
Enter a Minimum thickness in the Options panel or use the default value.
You can also click the arrow to open a slider for setting the Minimum thickness. The Thickness display changes dynamical as you drag the slider.
(Optional) Click the 3D Printing Direction tool guide and select an face, edge, point or axis parallel to the printer vertical direction.
Select a faceted or solid body.
Although solid bodies can be selected in the Thickness tool, they will produce no results.

The results are shown shaded with areas that are less than the Minimum thickness shown in red. An example is shown below.