Thanks to everyone who was interested in my searches!

The study shows that the dimensions, thickness and rigidity of the plastic are in a rigid relationship and allow only small variations from the optimal values.
I have placed one of the variants of the membrane cell. Unfortunately, I have not yet found 0.3mm plastic in the local availability and I do not have a 3D printer that is supposed to print transparent light-scattering elements.
I am considering the issue of printing in a printing house with a solvent or sublimation printer.