3D Primitives and Conversions - Autodesk AutoCAD 2013 Practical 3D Drafting and Design - page 159

Note
The converted solids maintain layer, color, and other general properties from the
original objects. The current layer is not applied.
Converting objects to surfaces
The next command converts some type of objects to surfaces.
The CONVTOSURFACE command
The CONVTOSURFACE command (no alias) converts the following objects to sur-
faces:
• 2D open polylines with nonzero thickness
• Lines and arcs with nonzero thickness
• Regions
• Planar 3D faces
• 2D solid objects (the SOLID command)
• 3D solids