Leaderboard

Can you post the .dwg with the model here? As above run LIST on the object.

That would depend on what field you work in. For me, working in the chemical engineering field, it was process piping and instrumentation symbols such as valves, pumps, filters, pressure gauges, flexible connectors, hose connectors, etc. When I worked in the civil engineering field it was surveying symbols such as poles, hydrants, catch basins, manholes, trees, traffic signs, fences, mailboxes, water valve boxes, etc.

Look in properties and see what it says it is. Should be a 3D Solid.

Are you certain it's a 3D Solid? Where did it come from? Did you create it in Autocad or is it imported from another program? What happens when you run the MASSPROP command? Does it give you the error that no solids were selected? Can you provide the drawing file?