A scaffold holding one or more ion-conductive ceramic membranes for use in an electrochemical cell is described. Generally, the scaffold includes a thermoplastic plate defining one or more orifices. Each orifice is typically defined by a first, second, and third aperture, wherein the second aperture is disposed between the first and third apertures. The diameter of the second aperture can be larger than the diameters of the first and third apertures. While at an operating temperature the diameter of the ceramic membrane is larger than the diameters of the first and third apertures, heating the scaffold to a sufficient temperature and for a sufficient time causes the third aperture's diameter to become larger than the membrane's diameter. Thus, heating the scaffold may allow the membrane to be inserted into the orifice. Cooling the scaffold can then cause the third aperture's diameter to shrink and trap the membrane within the orifice.