Opaque PETG fillament

Hello to everyone from a newcomer to 3d printing.I have a requirement to 3D print parts for an optical device and advice given is to use PETG. All filament suppliers seem to provide translucent filaments, or it may be that I don't know what to look for.Any help will be greatly appreciated.

You should consider the optical properties you need - Transparency, color, opacity, or anything else. Transparent filaments like PETG, TPU, and some PLA blends allow light to pass through well.