Mesh with constant thickness

[gaba]

Whenever I model terrain, I dream of an additional feature that would be useful, e.g. for convenient cutting of roads, various surfaces (etc.) in the terrain mesh, so that it would then also be visible in cross-sections (e.g. by using SEO operations). This is a mesh of a given thickness: 

[Jerryjb]

By allowing the bottom to be defined similar to the top, this could be extremely powerful in calculating earth volumes and defining grades at different strata and stages throughout the construction process.  For our digital construction age for machine control and quality controls, AR and XR visuals this would be a great add.