Why can't I convert this polyline to a mass element?

[Anonymous]

I've been fiddleing around and I am stuck, I cannot convert this polyline to a mass element.

I'm trying to make a walkway up, around a small lawn fountain and to the door.

I converted the lines from an spline to a polyline, then used the close option for polyline-edit.

Here is an imgur album showing the steps I am taking: http://imgur.com/a/Dw4QC#0

Google Drive link to the drawing: https://drive.google.com/file/d/0B9lShezVTkCDQnNWdUplRkl6Yms/view?usp=sharing

[leothebuilder · Accepted solution]

I would redraw that in lines and arcs.......and instead of a polyline with 400 segments and vertices you will end up with

about 12 sements. Covert those into a polyline and extrude to a mass element 

[Anonymous]

Thank you very much. Barely took 5 minutes, not sure why I didn't do that in the first place.

I think it turned out nicely.

edit: Heh, I gave you your 69th kudo, neat.