A theoretical and experimental study of thermosensitive resins used in thermal stereolithography is presented. The process of local curing through the application of infrared radiation, which has proved to be useful in a new technique for the making of prototypes by means of selective heating with C02 laser (10.6um), is studied. The ideal composition of the thermosensitive resins has proved to be 10 parts epoxy, 1.4 part diethylene triamine (the curing agent) and 0.7 part silica powder. A physical theoretical model is applied for control of the parameters which influence the confinement of the curing in the irradiated bulk. A mathematical model is applied too; it was developed through the resolution of the heat conduction equation dependent on time in cylindrical co-ordinates, which enables to determine the behaviour of curing in terms of irradiation conditions.