A shape-formable apparatus comprising fibrous material. The apparatus can have a first state in which the apparatus is formable into a desired shape, 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 include an envelope defining a chamber, a port positioned to fluidly couple the chamber with ambience, and a fibrous material positioned in the chamber. The fibrous material can be substantially less formable when the apparatus is in the second state than when the apparatus is in the first state.