I have a 3D sketch of something quite similar to what you would use if you wanted to make a roll cage with the weldment tool.  I however would like to take the outside of this sketch and coat it with sheet metal.  Preferably it would actually use the sheet metal tool so I can create an actual flat pattern.  I have taken the approach of crating planes on all of the surfaces created by the 3D sketch and then using the 3D sketch to create a 2D sketch then making a piece of sheet metal from that sketch.  This method does box everything in, but doesn't look good and the edges are messy.

This seems like something that should be able to be done, but I cannot figure it out.  Any help would be very appreciated.