anybody ever made a tonnuea cover?

Thinking metal, as I would want the scoops (ala T-bird)for my drivers side headrest(no passenger headrest). Would render the top inoperative when installed which could suck in rain. Have thought that it could be tied down with the rear seatbelts and possibly add straps at the front seat belt mounting points. Maybe I will have to buy some metal conduit and play around and see what I can come up with.
Would love to replicate the Daroo, but I lack the right combination of skills and money, and I don't have the guts to cut up my convertible.