I never said you had to design the frame.
Just, if you have access to the frame, you should be able to try putting it together INSIDE of the frame. Like place the pieces inside, and see how they go together inside it.
It may or may not be possible, but there has to be SOME trick to it.
“…Judge not what a man has done, but judge what he could have done if he was a different bloke altogether. For art thou a leper? And a leper can changeth his spots…” --Rudy Wade, Misfits (Series 4, Episode 8)