Cannot measure volume on a closed mesh
If you receive a message "element not valid" when trying to measure the volume of a closed mesh. Then the mesh is more then likly not fully closed eventhough it might apear to be.
1. Use 'Mesh Audit' tool on the mesh and see how many Voids are found in the mesh.
2. Close any voids in the mesh with the 'Stitch into Mesh' tool.
Note that it might be easier to see voids in the mesh if you use a Display Style > Modelling / Monochrome or similar.
3. Use the 'Mesh Audit' tool again to check and see if voids are still missing.
4. If you cannot locate any missing voids then use the 'Close Mesh Voids' tool / set perimeter to f.ex. 10 and see if this works.
5. When the last void in the mesh has been closed then you can use the 'Measure Volume' tool.