CADTools

CadTools is developed for Civil Engineers using AutoCAD.
With CadTools you can create your own surface models based on objects in the drawing or import triangles from DWG (other civil software).

You can create profiles and cross-sections of multiple surfaces, calculate volumes and plot contours.
For minor design work the program can be very useful, it contains more than 50 commands mostly in real 3D to support your work.