The synthesis reaction chamber or flow cell is visible in Figure -23. The flow cell positions the synthesis surface at the exact focal plane of the relay, relining on a kinematic coupling with the flow cell holder. The three precision micrometer actuators for this coupling are visible in Figure . The flow cell is held in position against the actuators with a magnetic bolt that can be rotated into with two turns of a knob (shown in red). This approach results in a reproducible force between the mating parts, and therefore, more precise positioning. The flow cell holder is positioned using XYZ translation stages as shown in Figure -25. The material for both the flow cell holder and the flow cell was chosen to be titanium to reduce stress on the translation stages, for its relatively low coefficient of thermal expansion (~8.5 µm/m/°C), and for having a relatively high modulus of elasticity (~110 GPa). Aluminum, used extensively in the MAS 1.0 optomechanical system, was judged to have too high of a coefficient of thermal expansion and too low of a modulus of elasticity for MAS 2.0, due to the need to prevent image drift, and to keep the substrate sufficiently flat, respectively. Stainless steel was determined to be too heavy, both for the translation stages and for the user assembling the flow cell. Mechanical drawings and parts lists for the mechanical components can be found in the supplementary materials.