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We present new Spitzer 3.6 µm images of the 82 galaxies in the "Survey of HI in Extremely Low-mass Dwarfs" (SHIELD). Selected from the ALFALFA blind HI survey, SHIELD is a volumetrically complete sample of galaxies with HI mass reservoirs smaller than 2x107 M☉. These galaxies populate extreme portions of parameter space and they offer unique opportunities to explore the physical properties of very low-mass halos in the local Universe. The new Spitzer images allow us to measure the stellar masses of the SHIELD galaxies. We discuss methods used to remove image artifacts and to excise foreground and background contaminants. We then measure the total 3.6 µm fluxes of the systems and apply a mass to light ratio in order to derive their stellar masses. We discuss the application of this technique to the Leoncino dwarf (AGC198691, one of the most extremely metal-poor galaxies known), resulting in a stellar mass of 7.3x107 M☉. This work has been supported by NSF AST-1637339 and by Macalester College.