The present techniques provide systems and methods for assembling electrolyzers from parts which have internal structures that form fluid flow channels when placed adjacent to one another. In a contemplated embodiment, the assembly technique may use alignment bars, inserted through openings in the individual parts to hold the parts in alignment, while other structures apply pressure to hold the structure together. In another contemplated embodiment, the parts may be aligned by having ridges, or other protrusions, formed on the parts that mate with openings on adjacent parts. The applied pressure seals fluid flow channels formed in the electrolyzer and extending through the joined parts. The use of pressure to hold the structure together allows for the servicing and replacement of individual parts.