More acoustic element models:
https://3dsky.org/collection/shared/5390990 

Sound-absorbing light Wave by Hey Sign in size S
Felt color is easily customizable in Corona Color or Vray Color

Product on the manufacturer's website:
https://hey-sign-shop.de/en/Living/Luminaires/Ceiling-object-Wave-with-luminaire-square/1235708-LM 

3dsmax 2013 file and FBX with Vray materials
3dsmax 2013 file and FBX with Corona materials
Preview materials Corona
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All CoronaLegacyMtl materials compatible with Corona versions from 1.5

For Vray versions below 3.1, some materials may not show up in MatEditor and when rendering. To fix this, set the Blinn value in the BRDF section.