The present invention consists of a method and apparatus to efficiently coat architectonic moldings made of diverse materials, providing a versatile, and continuous production, where polystyrene stands out from different types of coating materials. The apparatus consists of a leveled table on which the pieces to be coated are placed, aligned to one or more guiding strips, and moved by a two-way drive system. The pieces are introduced into an extrusion chamber, wherein the coating material adheres to them, according to the desired thickness. Due to their characteristics, the apparatus and method of the present invention offer the following advantages: (1) versatility in the production because it allows simultaneous production of two or more models of different architectonic moldings; (2) efficiency in the production because it is possible to introduce two or more pieces to be coated towards the extrusion chambers per cycle of the apparatus; (3) efficiency in the production when maintaining a continuous process of production, operating each extrusion chamber independently, such that the method and apparatus continue operating during the time of preparation (change of model) of either of the extrusion chambers; and (4) greater possibilities in the characteristics of the applied coatings, because the pieces can be coated with one or two coating materials, according to what is required, during the same period of time, that is to say, during the passage of said pieces through the extrusion chambers.