In this article we present the mechanical design and the manufacturing of the support structure for the Reionization And Transients InfraRed (RATIR) camera. The instrument is mounted at the f/13 Cassegrain focus of the 1.5-meter Harold Johnson telescope of the Observatorio Astronómico Nacional at San Pedro Mártir (OAN/SPM) in Mexico. We describe the high-level requirements and explain their translation to the mechanical specifications and requirements. We describe the structural finite-element analysis and the boundary conditions, loads, and general assumptions included in the simulations. We summarize the expected displacements, rotations and stresses. We present the optomechanical components and the elements used to attach the instrument to the telescope. Finally, we show the instrument installed on the telescope.