ESTER (Evolution STEllaire en Rotation; Rieutord et al. 2016) is the first open-source, multi-dimensional stellar structure code. I am working with Jane Pratt and Maxime Stuck as a GEM Fellow at Lawrence Livermore National Laboratory to update the ‘microphysics’ of ESTER, with a focus on rapidly rotating stars. I recently implemented new, high-resolution OPLIB opacity tables (Farag et al. 2024) into the existing physics module, expanding the number of opacity mixtures available in ESTER, improving interpolation methods, and enabling the future use of user-provided opacity tables.