I made a rectangle shell. I would like to add an apron/flange extending from opposing ends and still keep the part one-piece. 
I made a rectangle shell. I would like to add an apron/flange extending from opposing ends and still keep the part one-piece.
See if this example using Jeff's method helps.
Matthew
You'll have to break that top surface into separate flanges in order to make it from one piece of sheet metal, perhaps as shown below.
Dwight
Assuming, of course, that he wants it to be sheet metal.
Yes, you are right.
I would prefer to vacuum-form from plastic once I go through my learning curve.
What version of SolidWorks are you using?
For a vacuum formed part you will want a bit of a draft angle on the sides.
Have you already started the part - can you attach what you have completed so far?
I might do this a bit differently than most - I would do a couple of Extrude features and perhaps split some faces and Shell.
If I knew what version of SolidWorks you are using - I could take the time to create an example. (see attached)
There are any number of ways to accomplish this. One would be to draw a sketch on the top edge of the shell that is the size of the flange you want and then extrude it, being sure to check the merge box.