Normally with the pile contruction you have the outer plastic shrink, and inside that a wax dip over the cells. Then you have the cells, made from a paper outer wrap covering an inside mix. Top of the cell is a zinc sheet with a carbon coat on the one side, then a layer of manganese dioxide mixed with ammonium chloride to make a nearly dry paste, and topped with a graphite powder block. they are layered then pressed into a block in a die to get the cells to ontact, then wax dipped for protection from drying out, then sealed with a plastic shrink and then placed into a case. The contacts on one side are just a set of teeth onto the zinc plate and the other side a steel strip with teeth onto a zinc plate with the carbon contacting the carbon anode of the bottom cell. Simple to make, and as it is mostly dry you have little issue with it leaking.
the cylindrical AAAA cells have 2 methods I have seen, either a set of tabs welded to top and bottom of each cell to interconnect, or more commonly these days a simple pressure connection with a silicone pressure plate and a plastic sheet with contact strips on it to join the cells.