An enclosure for an electrical energy storage device such as a wet tantalum electrolytic capacitor or an electrochemical cell such as a lithium/silver vanadium oxide cell is described. The enclosure comprises two metallic casing components or portions. The first is a drawn member having a planar face wall supporting a surrounding sidewall and is shaped to nest the anode, cathode and intermediate separator components. The surrounding sidewall has an annular flange at its outer periphery. A mating cover is a stamped planar piece of similar material whose periphery fits inside the annular flange or rim as a complementary piece.