Hypothesis: Sessile droplets of contrasting volatilities can communicate via long range (similar to O (1) mm) vapour-mediated interactions which allow the remote control of the flow driven self-assembly of nanoparticles in the drop of lower volatility. This allows morphological control of the buckling instability observed in evaporating nanofluid droplets. Experiments: A nanofluid droplet is dispensed adjacent to an ethanol droplet. Asymmetrical adsorption induced Marangoni flow (similar to O (1) mm/s) internally segregates the particle population. Particle aggregation occurs preferentially on one side of the droplet leaving the other side to develop a relatively weaker shell which buckles under the effect of evaporation driven capillary pressure. Findings: The inter-droplet distance is varied to demonstrate the effect on the precipitate shape (flatter to dome shaped) and the location of the buckling (top to side). In addition to being a simple template for hierarchical self-assembly, the presented exposition also promises to enhance mixing rates (similar to 1000 times) in droplet-based bioassays with minimal contamination. (C) 2019 Elsevier Inc. All rights reserved.