*2.4. Casting Process*

Thermally prepolymerized PMMA precursor was polymerized for 10 min between a commercial PMMA substrate and a metal microstructure using a UV-light source (Superlite 400, Lumatec, Oberhaching, Germany) at 415 nm (exposure intensity: 5.8 mW/cm−<sup>2</sup> ). A rectangular structure (2 <sup>×</sup> 12 mm<sup>2</sup> ) was cut out from a stripe of scotch tape (48 µm thickness), which was used as both mold and spacer between the metal microstructures and the PMMA substrate.
