Volume from surface meshes in Leapfrog Works


Is it possible to create a volume which is defined by other intersecting meshes? I would like to know the volume of rock which is defined by a couple of surfaces that I can define by planes that I convert into meshes.

How would I do that in Leapfrog Works?

I manage to cut a mesh with another (Meshes - Mesh Operations - Clip Mesh) which gives me however a correctly cut mesh but which is open instead of closed by the bordering meshes I used to cut that mesh).

Thanks, Manfred