In 1935, Antonio Ruiz painted El maquetista (The Model Maker), a rare depiction of a brown-skinned person as a producer of the most avant-garde architecture of the time. As a portrait of a model maker, a profession seldom portrayed in art history, this painting also offers testimony of Ruiz’s role as a teacher in the Escuela Superior de Ingeniería y Arquitectura (ESIA), where he was head of the model-making workshop since the school was founded in 1932. The current article highlights the importance of the ESIA in professionalizing the lower and racialized classes of postrevolutionary Mexico, as well as the use of functionalist architecture as an instrument to spread socialist ideas. El maquetista helps us understand Ruiz’s political views and the close relationship he held with functionalist architects of the 1930s, fellow professors whose projects students used to create models to scale.