Wow... this image posting system is not user-friendly.
Anyway, Finguy, thanks for the suggestions. I'm not familiar with plasticine, but I'll look into that.
I may not be understanding you, as I've never built a car before. I don't know that I can really "use the existing shells", as the light doesn't currently have shells. They are more a "tray" than a "shell".
I purchased lights, but they are the OEM Pontiac lights, which I bought for the popup hinge mechanism. The OEM Fiero lights are not the right shape, and I think they are too narrow and too short to fill the Testarossa opening. I will need to find or make a shell to attach onto the mechanism.
Bodyman,
Thank you for the suggestion on where to find lights in your build thread. I have referred many times to your build thread. An excellent resource! I will go back and look at it now.
I prefer the look of the original 1984-1988 (?) Testarossa model, like your's. Mine seems to be a composite of the second and third Testarossa models (TR512 & 512M). Anyway, these grilles won't work for my rear lid, as my rear lid "wings" are not flat on top.
However, they would probably work for your car, at least based on this photo.
The price is MUCH lower than T Rutlands, and a couple of the other places I've seen. He has both left and right grilles, $200 each. I usually see them listed for $400 to $700 each.
Rear lid grille