Thermal evaporation furnaces are essential tools for the controlled growth of oxide-based micro- and nanostructures. Their core function is to provide a high-temperature environment where solid precursors are evaporated and transported in vapor form, enabling their condensation and crystallization on selected substrates. By adjusting parameters such as temperature, atmosphere, and growth conditions, researchers can tune the morphology, composition, and properties of the resulting materials. The fundamental principle relies on the transformation of solids into vapor at elevated temperatures, followed by their deposition through two main mechanisms: Vapor–Solid (VS), where species condense directly on the substrate, and Vapor–Liquid–Solid (VLS), where a liquid catalyst droplet guides anisotropic growth such as nanowires. Both processes are governed by thermodynamic and kinetic factors that ultimately define the structure and quality of the material. Why they are important: Thermal evaporation furnaces enable the synthesis of advanced functional oxides with tailored optical and electronic properties, opening pathways for new devices in optoelectronics, sensing, and power applications. At the same time, they provide a versatile platform to investigate fundamental growth mechanisms, phase stability, and defect formation. In this way, thermal evaporation furnaces serve not only as practical synthesis tools but also as key instruments for discovering and engineering the next generation of functional materials.