The plan of operation of the industries shall be to manufacture supplies such as brooms, brushes, mops, mattresses, desks, and office, school, and other furniture which are in the capacity of the blind to make and which are extensively used by the various departments of the state, its political subdivisions, and its educational, penal, and other institutions; provided, however, that this enumeration is partial and not exclusive of articles that may be manufactured in the industries.