PURPOSE: To obtain products of complicated shape not causing a joint after fusing by placing plate glass on the top of a cast mold, masking the top of the plate glass except a desired shape part, scattering powdery color glass on a not masked part, then removing the masked part and then heating to high temperature.

CONSTITUTION: Plate glass G is placed on the top of a cast mold A, the top of the plate glass G is masked M except a desired shape part of the plate glass, a given amount of powdery color glass C is put on a not masked part 5, the masked part is removed, the plate glass is fed as it is to a furnace and heated ≥ the melting point of glass in the furnace to fuse the color glass C to the plate glass G.