Microfabrication and cell culture insert modification for in vitro crypts. a, Photolithography workflow to produce micropillar master molds of 1002F resin. b, Soft lithography replica molding of PDMS to produce stamps that will be used for micromolding collagen. c, Cell culture insert modification and in situ micromolding of collagen. d, Completed cell culture inserts for in vitro crypts, and characterizations of the micromolded collagen scaffolds. Panels b and d are adapted from refs. 24 and 37 with permission from Elsevier and the American Chemical Society (Copyright 2019), respectively.