How to draw polygon mesh in cad20 12?

There are entities and grids in three-dimensional space. Entities have quality characteristics, so you can query the volume, such as multiplying by the specific gravity to get the weight. Grid, just the surface. Three-dimensional solid and mesh are in three-dimensional space.

Also, two-dimensional plan is used to express three-dimensional wireframe, not three-dimensional space.

The specific choice depends on the expression requirements.