An apparatus and method for replicating the profile of a plantar surface of a foot are provided. It has particular application in the production of footwear insoles, the apparatus comprises a pressure resistant container (2); an elastic membrane (3) sealed to an open face of the container, thereby defining a variable volume chamber within the container; means for reversibly introducing fluid (15) into the chamber; a bed of elongate rods (13) of substantially equal length, in which, in one configuration, the rods can slide freely, one relative to another, along their length; and clamping means (10) for reversibly clamping the bed of rods so that the relative sliding movement of the rods is resisted; the bed of rods being arranged, in use, outside the container so that ends of the rods abut the face of the membrane. In this way, a positive and negative mould of the surface can be formed.