Preferably, aluminium cans used, in which producers electrolytes supply. Anyway, I have always refrained from transfusion of electrolyte into another vessel. In extreme cases, you can use a voided vessel from under another electrolyte. Before this, it must be thoroughly washed (distilled water, alcohol) and dried. Polyesters cannot be used. Polypropylene or polyethylene can be used, but for what purpose? In a few days, nothing will happen, but is unknown how it behaves with prolonged storage of electrolyte. It is very wrong to put the results of long-time electrochemical experiments in dependence on unaccounted factors. In good laboratory, empty branded cans should present. Additionally, do not forget about a good and clean lid...