Not a new idea. Look at old Fords and Lincolns. They had a metal roof that folded up into the trunk.
To make you to fit a Mustang would be a huge - and expensive - undertaking. The Mustang trunk is so small, it might not even work.
You could also make a removable hard top out of fiberglass. Take a look at the old Corvette's, '56 T-Bird, and even the LeMans top for the Shelby Cobra. That would be a hand made part, and you would not be able to fold it up.
__________________ .boB
'08 V6 Pony
'65 Monster FFR Cobra |