A mathematical process model that stimulates important aspects of stereolithography, a rapid prototyping technique used for the production of three-dimensional plastic parts, has been developed. The model consists of a set of coupled partial differential equations and considers irradiation, chemical reaction, and heat transfer in a vat of photomonomer exposed to a moving UV laser source. Laser motion occurs in a straight line (vector path), and the model thus simulates the production of a single strand of plastic. Numerical techniques are used for approximate solution of the model equations, and output includes spatial and temporal variations in conversion of monomer to polymer, depletion of photoinitiator, and variations of temperature along the line of exposed material. The formation of a temperature wave that moves along the line of plastic is observed, together with the fact that the leading edge of the wave is steeper than the trailing edge, i.e., the material heats considerably faster than it cools. The maximum temperature of the wave reaches a pseudo-steady state after a short time. The results have provided useful information concerning the temperature at which the majority of the polymerization occurs; provided information on overall transient temperature behavior; allowed computer prediction of stereolithography working curves (cure depth and cure width vs. laser scan rate); and afforded a means for evaluating the amount of reaction that occurs in the dark period after light exposure.