Coming from the M5 forums, we have a dedicated member (like yourself) who fabricates all sorts of parts for the E39 M5 (e.g., Front Lip, Rear Diffuser, Fog Light Cover, Rear Spoiler, etc.).

Here's some examples of his work:

SlimmBones Front Lip - BMW M5 Forum and M6 Forums

Slimmbones Rear Diffuser GB - BMW M5 Forum and M6 Forums

E39 (96-03) For Sale SlimmBones XL Foglight Cover - BMW M5 Forum and M6 Forums

I suggest you reach out to him for advice (he's a great guy and does amazing work).

His user id is SlimmBones and name is Rick.

His e-mail address is: [email protected]

Maybe you can work together