Draw your arc to the shape you want, use the revolve command, select 180 degrees, set the axis to revolve around, hit enter and your done...
I have it drawn in rhino 4 using the revolve command. If your going to make a mold, I would draw a box then use boolean difference to put the cavity in the box...... you need to cap the bottom of the canopy to make it a solid for the boolean to work.
I can email you the file, I dont know how to post it here.
mike sr
This is a snip of the canopy file in rhino.
mike sr
Loft command should work fine. If cplane oriented curves are open.
If you add profile curve somewhere in middle, you can use curve network command.
Enjoy! Just keep in mind that all input curves should be closed or open. Not mix them.