This will be a stackable, multiple piece water desalinator about the size of two Stanley cups stacked upon eachother.

 You, hypothetically, could put salt water in one of the containers, have it start to boil and a more durable yet still flexible plastic wrap type film will be able to catch the evaporated droplets left by the boiling saltwater and then the droplets will drop into a container above the bottom container that contains saltwater and then you will have fresh drinkable water. 

 It will be heated by a heating device at the bottom of the water desalinator powered by battery that will be well insulated and have a cooling system for safety and workability. That boils the saltwater starting the evaporating and condensation process. 

There will be left over brine/ salt from the evaporated saltwater which is where the base piece right above the heating device comes into play. The whole desalinator is detachable and in sections so you can take the base piece with the brine/ salt still inside and dispose of it thoughtfully. 

Theres also a top piece with a built in weight that pushes on the plastic wrap type film which is just meant to center the condensation so the freshwater falls into the center of the water desalinator instead of leak out the sides.