Two active cell structures are prepared each comprising anode/electrolyte/cathode layers, each anode and cathode layer having embedded spaced-apart physical structures therein. Two interconnect sublayers are prepared, each comprising a layer of non-conductive material with holes formed therein and a conductor layer formed on one surface. The sublayers are placed together with the conductor layers in contact and with the holes offset to form an interconnect layer, which is then stacked between the two active cell structures. The multi-layer stack is laminated together and the anode layer of one active cell structure and the cathode layer of the other active cell structure fill the adjacent holes in the interconnect layer. The physical structures are pulled out to reveal embedded gas passages, and the multi-layer stack is sintered to form two active cells connected in series by the interconnect layer.