A gasbag pressure (GBP) mechanism has been developed for patterning submicron patterns onto large concave substrate. The GBP mechanism consists of a pressure gasbag and a vacuum chamber system. It provides gradual contact, uniform pressure, and intact contact for imprinting patterns in the soft mold onto a concave substrate. The patterns on the soft mold can be successfully replicated over an entire photoresist-coated concave substrate. The accuracy of replication has been experimentally evaluated. (c) 2006 American Vacuum Society.