<p>The fabrication of microfluidic chips using mechanical micromilling offers a promising method for rapid prototyping. This study investigates the use of mechanical micromilling to produce microchannels in Polymethyl methacrylate for flocculant testing, which requires precision and smooth surfaces to ensure effective fluid flow and mixing. The dimensional accuracy of the fabricated microchannels was evaluated using a coordinate measuring machine, and surface quality was analysed through scanning electron microscopy and confocal microscopy. The coordinate measuring measurements indicated high consistency across most features, but significant deviations were observed in specific regions, suggesting challenges in achieving tight tolerances for certain geometric features. The scanning electron micrographs analysis revealed surface imperfections, including excess burrs and feed marks, which could negatively impact fluid flow in microchannels. Confocal microscopy confirmed the presence of high surface roughness, with pronounced peaks and valleys that could disrupt flow and increase resistance in microfluidic applications. The findings highlight the need to optimise process parameters to improve surface quality. Optimisation of the micromilling parameters and post-processing techniques is necessary to enhance surface quality for the microfluidic device to meet the stringent requirements necessary for effective flocculant testing.</p>