A versatile mask changer and evaporator has been developed for use in fabricating experimental thin film circuits. Composite masks consisting of a combination of movable wire grills and electroformed metal sheets serve to define the required patterns of metal, insulator, semiconductor, and photoconductor. Precision motion of a 3.81−cm sq glass substrate relative to the masks permits the deposition in one pumpdown of large area arrays and circuits having electrode spacings accurate to within 1 μ. The substrate is located within 2.54 cm of a viewing window to permit convenient microscopic examination of the evaporated pattern during deposition. The mechanical problems are to provide sufficient mask storage, which can be aligned accurately to each other within microns. This will be demonstrated in the case of two examples: the preparation of the integrated sensor (512×512 units, each containing active and passive elements) and the optical three−color stripe filter having each color 30−40 layers spaced within 8 μ side by side, up to 5.08−cm sq area.