Help with translucent backlight material

[HoppyHopp]

Hey, I need to create something like that:
https://youtu.be/hGHMHFNVTrs?t=176

A printed translucent fabric that is backlit.
I made 3 versions so far:

1. Version: with backlight it looks ok but without it doesn't look right




2. Version: with backlight it doesn't work, course how the translucent shader is working, without backlight it looks ok.



3. Version: looks kinda ok with and without backlight, but i don't know if this physically correct in anyway



I really need to get this as close to reality as possible, do you have any other idea approaching this?

[kintuX]

Why don't you simply ditch extra geo and do it in shader?
Unless you need to animate it.

[HoppyHopp]

Why don't you simply ditch extra geo and do it in shader?

Cause thats not how it is done in real world, as is said i need to get this as realistic as possible.
I choosed LuxCore and not Cycles for this project to get every bit of realism i can get.

[kintuX]

A small advice...

Do note and save yourself from walking down too deep into an endless rabbit hole... Whatever we observe, our perception is biased. Nothing, but reality itself, is real. And for us still, it's all approximations (simulations) & representations (illustrations). Starting with mathematical shader models. Anyways since you care about such a detail as 'physically' (polygon) modeled shader, tell me then: what kind of panel LEDs are transmitting through. Do you know its thickness? What sort of emitter is it? What are its characteristics? What are foil & print characteristics? And so on and so on... finally then, the most influential stuff awaits... the environment. All of this matters in reality. In here (in our world), compromises must be made. This is the balance artists make individually.

Hope you get what you seek for.

PS
It's worth checking the Power of "Good Enough" (from Arrimus 3D on YouTube)