   Determining a Mesh from an internal 3D structure
  I have a 3D structure consisting of spheres, tubes, cubes and rectangular columns.  I wish to determine a closed mesh that will encompass the 3D structure with some minimum distance from the internal structure.  The mesh itself has nice Bezier curves and could form a torus or other shape with holes.  In addition to the mesh, I need to know the volume that the mesh encompasses.How do I go about determining the geometry of the mesh?  Is there a library I can buy or must I get a mathematics guy to write one for me?If I pay somebody to write it, approximately how many person-weeks of work is it to write the logic if the technology is DirectX and .Net?   