Not quite sure I understand what you are asking for.  A light weight hard top, or like a tonneau cover?

Corveddie

I have a 96 LT4 CE coupe.  I use a "pop-top" It's a "white" cover that attaches to the side mirrors and covers the
top and attaches to the rear window.  I use this most of the time when I park out of the garage.  It keeps the
interior cool and clean.

There is also another top that is available for C4's  It's a "harder" top that is lightweight that you place on
the top.  It cannot be used while the car is in motion though.  It's just to cover the top while parked.

Both are available on line.

Regards

Darryl