Abstract: Customizable hydrogel patterned into arrays of microwells, microchannels, or other microfeatures, and a process to prepare patterned hydrogel adherent to a solid support, are provided. A pattern of light is applied to photopolymerizable hydrogel precursor solution on a solid support, resulting in the formation of a patterned hydrogel bonded to the solid support. Hydrogel precursor solution is held by a ring of a customized height secured to a photomask or to a surface allowing transmission of a pattern of light. This process allows for facile customization and repeated fabrications of hydrogel microwells of desired heights and geometries with a micron or submicron scale resolution, adherent on various solid supports.