A volumetric liquid meter of the oscillating piston type having a chamber, includes a bottom portion, a fixed partition, a piston and a filter. The architecture includes cores for plural test layers, a top-level data register, and a top-level test controller. A plurality of shutters is removably mounted over the plurality of niches by a concealed mounting system. The mechanism also includes an actuating structure operable to selectively move the cap between an engaged position to press against the printhead and a disengaged position spaced away from the printhead. The wafer remains in the growth chamber throughout the method.