Meshes in Rhino

https://sites.google.com/a/uic.edu/uic-fab-lab-1330/3d-printing-2/how-to/setting-up-a-stl/MESHES_Horizontal.png?attredirects=0

About Meshes

Before a model can be sent to the printer, it must be converted to a mesh (.stl), which transforms smooth surfaces into planar polygons. Although saving a model to the .stl format automatically converts it to a mesh, converting it in Rhino allows greater control over the outcome.


How to convert to a mesh:

To convert your nurbs model to a mesh, type Mesh. The Polygon Mesh Options window will appear, with a slider that allows you to choose the resolution of the mesh. More resolution both improves the approximation of curvature and takes longer to process. Note that the surface geometry of your model determines the mesh geometry (see below). Irregular geometry will produce poor meshes at a low resolution, and may also remain visible at higher resolutions.