I use these plastic cards that are used for standard ID cards. These car be easily cut, bent and when sanded, they can be glued together strongly.
The end bits are drawn out and cut to shape. Leave out a little extra and then use sand paper to quickly remove the edges.
So I thought I could cut corners and use a Lego piece to act as a spoiler. Maybe if I used a purple one....
The end parts are on but need further cutting and sanding to give it the rounded look. Superglue is the proper adhesive for such plastic bits. Doesn't bond so well with metal though. Bonds your finger very well as i have found out several times.
A third raised edge added to complete the original look as well as add stiffness.
The spoiler is made of two strip laid on top of each to add strength and thickness. Much sanding needed to round the leading edges. The two holes are cut out to position over the stands.
Test fitting before further smoothing and final paint. Final sanding is done with 1500grit sandpaper to leave a smooth finish for the paint. Higher grit sandpaper is found in all car paint shops.
The end result speaks for itself. It's not exactly the same, but for three hours of work, it is close enough. It's painted metallic black and left without polish. The end parts are lightly dusted with purple. It's not the pearlescent color but for such a small part, it'll pass.