A method of preparing a device of a selected material to have pores and pore interconnections of predetermined sizes and shapes includes the steps of forming a selectively removable open-celled porous mold form of particles which adhere to one another, with the particles corresponding to the predetermined pore sizes and shapes, and interconnections between the particles which bind them together in the form in which the connections correspond to the predetermined sizes and shapes of the pore connections. Also included are the steps of filling the vacancies between the particles and connections of the form with the selected material, and then removing the form to leave the selected material. The resulting device is at least partly porous, the pores and pore interconnections corresponding in size and shape to the particles and connections respectively.