A method of infusing, infiltrating or impregnating a three dimensional printed, free-form fabricated or additive manufactured object having pores or voids in or between particles or sheets of material from which the object is manufactured may include infusing the object with a thermoplastic material. The thermoplastic material may be a linear or branched semi-crystalline aliphatic polyester with a melting point of between 40° C. and 65° C. which may have a solidification/crystalisation point between 20° C. and 40° C., and which may be introduced under controlled conditions of temperature and pressure. The thermoplastic material may be caused to penetrate the object by immersing the object in the thermoplastic material and controlling the frequency and amplitude of pressure oscillation to ensure sufficient infusion into the object to penetrate the pores or voids by at least 10% and bond particles or sheets of material from which the object is manufactured.