A shape-formable apparatus comprising locking sheets. The apparatus can have a first state in which the apparatus is formable, and a second state in which the apparatus has the desired shape and is substantially less formable than in the first state. The apparatus can further include an envelope defining a chamber, a port positioned to fluidly couple the chamber with ambience, and at least two locking sheets positioned in the chamber in an at least partially overlapping configuration. Each locking sheet comprises a major surface, and at least a portion of each locking sheet can be patterned to include solid regions and open regions, the solid regions being movable with respect to one another within the major surface.