We are currently using one of Al's patented car covers. The tarp was too big, so we cut it down and in order to keep the eyelets, cut the tarp lengthwise down the center and taped it together with good ole' duct tape.
The duct tape worked so good, it got me to thinking. There was an Alpine in Winona that has a custom top cover. Here is a small picture of ithttp://www.sunbeamalpine.org/forum/attachment.php?attachmentid=3330&d=1315234070
It is the car in the right side of the photo. Unfortunately, it is small and hard to see any detail. It is made of upholstery grade plastic material and sewn together. It slips over the convertible top. I am thinking of making one by cutting up a tarp and putting it together with duct tape. It could be made from three pieces of tarp. One would go over the top, covering both side windows. The second would cover the windshield, the third piece the rear window. An alternative would be the long piece would cover front and rear windows, the other pieces the side windows.
Either way, Red Green would be proud.
Bill
Edit: Murrry's car is the one I'm referring to. Unfortunately, the link I posted will not work. Try here:
http://www.sunbeamalpine.org/forum/showthread.php?t=16849 and click on the photo in the center.