Hey hey,
Check out our How to Make Iridescent Materials with Thin Film tutorial: Chaos Docs (for 3ds Max users).
It shows you how to use VRayMtl’s Thin Film layer in V-Ray for 3ds Max to create iridescent surfaces such as soap bubbles and pear-like surfaces. The tutorial includes 3 different workflows: from simple to complex
Kind regards,
Gergana