All you need is a bowl, ice, water and salt.
The second law of thermodynamics states that the entropy of an isolated system never decreases, because isolated systems always evolve toward thermodynamic equilibrium, a state with maximum entropy.
Salt causes the ice to melt faster but to do this it needs to absorb heat energy from wherever possible – here also the can . A 50/50 mix of ice and water is a good rule of thumb. Stir them all around for 2 minutes. By stirring, you’re using forced convection to speed the transfer of heat out of your drink and into the ice water solution.

When salt is dissolved in water and then is frozen, it takes a lower temperature to freeze the solution. A sodium chloride solution will freeze at -10 C, which is 10 degrees colder than the freezing point of pure water. Sodium chloride (NaCl) provides two ions for every mole of salt dissolved. Road salt, or rock salt, is calcium chloride (CaCl2) and provides three ions for every mole of salt dissolved. The more ions present, the lower the freezing point of the solution.