Originally Posted by Pirates55
This is a sketch of what I want to build but I'm afraid the weight will be over 400lbs. I'm getting pricing on aluminum tubing now to lower the weight.
Your drawing doesn't look square. I'd suggest you go with a roll up canvas/vinyl material. With a system designed by the poster who gave you the outside link. Your issue, if its like the picture posted, is no sides are plumb or square.
All those angle calculations, to close that opening, and make it look good, would give the most expierenced carpenter a run for his money.