Colloidal monolayers are included in an increasing number of technological applications, from biomimetic and functional coatings to photonics and sensing devices. With the idea of patterning ordered monolayers on a substrate in a direct and straightforward manner, we developed a novel methodology that allows the two-dimensional self-organization of colloidal particles at the a/w interface of a hanging drop and their direct deposition on the targeted substrate upon drop evaporation. The method offers several advantages, including simplicity, versatility in terms of particles and substrates properties, and the ability to obtain ordered monolayers as well as polycrystals of complex structures. The size and crystalline morphology of the deposits was shown to depend on various factors such as particle size, density, concentration, and drop volume. Different strategies, including tuning particles/surfactant concentration or control of wetting properties, were employed to achieve the desired deposition outcomes. Through the exploration of the physico-chemical determinants of the self-assembly mechanism, we found that the adsorption of repulsive particles at the air/water interface was crucial for the formation of ordered monolayers, and this was made possible by addition of micromolar concentrations of a conventional cationic surfactant to anionic particles. Following a similar mechanism, we hypothesize that the method might also be applicable without surfactants to pattern particles that spontaneously adsorb at the fluid interface (such as cationic or amphiphilic charged colloids). Gravity-driven sedimentation of particles was also shown to play a role in the rapid formation of monolayers. Demonstrated with silica particles of different diameters (from 300 nm to 2.4 µm) and larger anionic polystyrene colloids (diameter 5.1 µm), the method thus appears to be readily applicable to any kind of particles capable to sediment in water. The deposit morphology was also influenced by drop curvature and particle number. Particularly, the use of low-wetting substrates with high drop curvature enhanced the packing forces and led to the formation of highly ordered structures composed of small crystallites, while pinning of the contact line on certain substrates results in lower density of the deposit and larger domains with local defects. Demonstrated on three kinds of surfaces, polystyrene, PDMS and glass, the established role of the substrate not only allows one to envision enhanced applicability on other substrates (e.g., metals, biomaterials) but also provides guidelines for tuning substrate properties favoring a desired deposit morphology. Additionally, we showed the possibility to easily adapt this "lowtech" method for the controlled fabrication of complex patterns such as: (i) phase-separated crystal monolayers of binary mixtures, (ii) multi-layered crystals with independently ordered layers thus forming Moiré patterns, or (iii) exotic structures such as iris-like patterns composed of polycrystalline rings displaying vivid structural colours. Consequently, we envision that a number of possible applications can be targeted by this method, exploiting any aspects of its versatility, simplicity, tunability and/or adaptability. This ranges from low-cost surface patterning and biomimetic materials self-assembly to photonic devices and other advanced functional materials fabrication. For example, polycrystalline colloidal deposits can be used for anti-counterfeiting labels due to the formation of unique patterns, providing an easy readout through structural colours and unclonability. To conclude, these results represent a simple yet impactful solution for the assembly of functional 2D materials, combining predictable physico-chemical interactions with a trivial deposition method, in line with the development of novel, yet simpler, routes to advance in materials science.