Is it mandatory to use the ACCUMOLD code 28000x as a plastic chamber or can I use another plastic case ? If yes how deep should it be? Thanks.

It is not mandatory to use the Accumold chamber, but the datasets and algorithm are correlational with each other.  That means that if you change the chamber then the datasets themselves are likely going to change because of the physical properties involved, and because of that the algorithm would most likely need to be tweaked and retuned for certain parameters.