PURPOSE: To simplify drawing as to the molding of a three-directional structure by arranging a rope on the internal circumference of a main mold with a formed resin- cloth-resin layer and then by pressing a male mold coated with resin against a female mold with a piece of bellows-shaped paper stuck to the rope.

CONSTITUTION: At the internal circumference of female mold 1 with a layer, made of thermally-softening synthetic resin 2, cloth 3 and resin 2, formed on a main mold, rope 4 with a knot at its terminal is arranged by inserting. A piece of paper 5 folded in a bellows shape is arranged at an uneven interval opposing to this rope 4. Then, the male mold provided with the resin layer is pressed against this female mold 1. Sand is packed surrounding this mold to form sandmold 7. Next, the open part of the mold is broken and rope 4 is pulled out while it is heated up to a temperature of approximate 100W130°C. As a result, the mold softened by heating comes out together with rope 4 being disintegrated, so that the sandmold will be completed. This mold simplifies the drawing of a three-dimentional structure such as a propeller blade.