A protective device for an internal resource protection in a network and method for operating the same is disclosed. The modulator changes the apparent orientation of one retarder stack relative to the other so that, in a first switching state of the modulator the two retarder stacks cooperate in filtering the spectrum of input light, and in a second switching state the two retarder stacks complement each other, yielding a neutral transmission spectrum. The sheet is elongated to form the uneven surface simultaneously with the through holes at the boundary portions between the higher density region and the lower density region. For instance, certain disclosed embodiments incorporate semi-permeable membranes to transfer target substances from one fluid to another. A machine for carrying out the method is also described.