Beyond their fundamental appeal, microswimmers are interesting for a range of applications ranging from targeted drug delivery (3), to environmental remediation , and even energy conversion , as they enable directed transport of matter at small scales and induce the mixing and pumping of fluids without external agitation . Janus microswimmers are arguably the simplest class of microswimmers. In Janus microswimmers, surface patches with different physicochemical properties induce the self-generation of asymmetric gradients, in turn imparting propulsion . Among those, chemical microswimmers exploit the catalytic decomposition of chemical fuel, e.g. hydrogen peroxide catalysed by a platinum surface, to generate local chemical gradients. However, even these simple microswimmers suffer from a very low throughput, as attaining patchy surfaces for large quantities of catalytically-active particles is synthetically challenging and physical fabrication methods, such as metal deposition, are only able to provide minute particle quantities at the expenses of a large waste of catalytic material . In a recent advance in the state-of-the-art of microswimmer synthesis, Archer et al. demonstrated the scalable fabrication of Janus chemical microswimmers by functionalising particles confined on the surface Pickering-wax emulsion droplets with a two-step nanoparticle seeding and film-growth protocol . However, this approach involves a poorly controlled reduction of platinum (Pt) nanoparticles from solution, requiring a significant use of expensive and toxic platinum salt precursor, as well producing undesirable nanoparticle waste . Furthermore, the approach as described is limited to the growth of platinum films.