Thank you for the answer. Its a little bit complicated, but i try to describe it. I do not want to make a dewar, because i do not have the possibility to make the vacuum. I have the freezer from the picture the link i posted to. it has a top, which is made from glass. I have to made a construction for this, one part of which will be put inside and the motor, which should drive the mechanism should be outside. To avoid of destruction of the parts, which are outside of the freezer, i want to make a top between the inner and the outside parts, which will be placed between the inner parts and outside mechanism. The freezer as itself exists, but i have unfortunately no access to the freezer (please do not ask why.) Because on the picture it seems that as the top is used glass, i think a vacuum isn't needed, but i do not know how good it isolates. That is why i am asking, is it possible to make the top from periflex to isolate (to keep cold inside or get the outside parts at least to -10°C) and what thickness the layer should have?
I would also apprechiate other suggestions. Unfortunately i do not have the possibilities to make very complicated constructions, like vacuum. I don't think liquid nitrogen is need for the isolation, because it is used as the cryogen.
Summary: Freezer/Dewar exists, Question how could be the top be constructed (which material, calculation thickness, vacuum not possible)
I can not give more details.