Film width mask

Recently I've been working on some holofoil-y iridescent stuff inspired by my buddy Stu.
However, I wanted to bring something new to the table and I figured I'll try to add a bit of extra detail to film width.

First I created a simple repeating pattern in black and white and applied it Octane Metal material's film width input. It probably goes without saying, but this really didn't do much for the material. There is a difference but 0% and 100% aren't very useful values. Yet.

The next step was to add a bit of control. I tried passing my pattern through the clamp node, but due to the fact that Octane's float values are non-linear, I found it somewhat frustrating to adjust the values. I could have passed RGB spectrum nodes into it, but I found it simpler to use gradient node instead.
On top of easier the easier nature of good old RGB sliders, gradient node can also be used with mask images that have more values. It's a win-win.
I also set film width IOR to 1.10 from default 1.45 since lower IOR gives a stronger effect.

Now that I had basic control of the mask, it was time to apply it elsewhere. I used another gradient node to control the roughness of the material and added transform node to downscale the texture for nicer tiling on the object. Next stop, environment! HDRI is cool, but a while back Stu sent me a small pack of very vibrant textures, so I applied one of them as an environment. Film width looks nicer with more curves, so for the sake of this guide, I added displacer effector to the sphere to make it look nicer.
I also attached the mask to bump input, but it doesn't really do much at this scale.

At this point the "look development" was done and I rendered a couple of pieces with it and used similar setup on Octane specular material without the roughness.

However, I wanted to try something more with the style. First, I replaced the mask with one of the KidPix pattern recreations. For this guide I also created a simple cloth object to further illustrate how curves work film width. I added a very bright and saturated teal to diffuse and set the specular map float value to 0.88. This blends with the film width and slightly washes out the colors, but I found it slightly more pleasing this way.

Now, at this point I was satisfied with the look and made a few renders with it on cloth simulations. If it goes further, expect updates. If not, maybe you can improve it. ;)

Good luck!