Making tinfoil material in Vray is not difficult. It is just a Chrome material. But it will be a little tricky when you need to create a crumpled tinfoil. In this tutorial, I am going to show you a way to create procedural crumpled tinfoil.
Make sure you are using Vray as your render engine. Once you have learned the technique, you can do it in other render engines as well. Open Material editor. apply VRayMtl to one of the free sample slots. Name it as you wish. I chose Tinfoil.
Tinfoil material is same as Chrome or aluminium material. Change Diffuse Color to black. Reflect Color to White. Make Sure Fresnel reflections is turn on. Change Fresnel IOR to 20.
We need to give a bumpy noise to our material. Add Cellular texture to the Bump map.
In Cellular Parameters, choose Chips as its characteristics. Reduce Size to 1. You can try different values but remember this bump map is for small noise on tinfoil not the major ones. Turn on Fractal option. Change Spread to 1.
Back to VrayMtl material. By default, Bump map value is set to 30. Increase it to 100. Apply the material to your object and render it. You can see we already made a good crumpled tinfoil. But I want add some big chunks on the object.
Copy the Cellular bump map on Displace map. Make sure you are using Copy method. In the displace Cellular map, just increase Size. I change it to 10. You can try different values.
Before rendering, it is better to disable Bump map so you can just see Displace effect.
Render your scene and see the effect of displace Cellular.
If you like the size and its strange on Displace map, then re-enable Bump map and render your final work.