I don’t know if they had batteries then but they used static generators such as the Whimhurst and Van de Graf generators. A cheaper way to make a capacitor is just use bits of wire, aluminum foil used for food and wax paper also used for food. All you have to do is make two plates near each other but not touching, roll the aluminum foil alternating with the wax paper, roll it around a pencil or something: foil-paper-foil-paper. Connect the two pieces of foil to the wires and you have a capacitor. The more surface area the plates have next to each other the more capacitance it has and the more energy you can store. Just be careful, applying high voltage from something like a static generator can build up the amperage into a lethal current. I would suggest using an AA battery for testing it. High current and voltage can electrocute you if it flows through your chest cavity (don’t hold one wire in one hand and the other wire in the other hand).
Scitoys has gallium that melts near room temperature and can be super cooled before it crystallizes, a gallium alloy that is liquid at room temperature, and an indium alloy called Field’s metal that melts in hot water. All three stick to glass and don’t need to be cooled to keep sticking, just melt it and smear it over the glass, it is good for making mirrors too.