This study presents the development of an innovative and sustainable model of an evolving and convertible cot that transforms into a Montessori bed at ground level. The aim is to enhance the functionality and sustainability of children's furniture, based on current market trends, competitor analysis, and manufacturing and marketing processes. Tools such as SolidWorks and the Finite Element Method (FEM) were used to assess the structure’s strength and stability, ensuring its safety for everyday use. The design meets technical and legal requirements, featuring telescopic legs for adjustable height, a folding side for co-sleeping, and a lower section that can function as a rocker or be fitted with wheels for easier mobility. The conversion into a Montessori bed addresses the child’s developmental needs by encouraging autonomy, cognitive growth, and well-being from an early age. To achieve an ergonomic design, anthropometric measurements were considered using data from the Andalusian Health Service and WHO growth standards. The cot measures 120 cm in its standard form and extends to 140 cm in its maxi cot and bed configuration, with a constant width of 80 cm. The result is a cot that grows with the child, offering flexibility to parents and extending use into pre-adolescence, thus promoting sustainability by reducing resource waste.