Three or more persons engaged in agriculture may form a corporation without capital stock for the purpose of marketing, buying, selling, treating, dealing in, handling or manufacturing agricultural products or by-products; the purchase of and selling or supplying to its members of surplus materials, including federal materials, machinery and demountable housing units, or other machinery, equipment or supplies; and the procuring of insurance for its members. Any such corporation may finance any of its activities, and shall be conducted upon a cooperative basis without profit to the corporation itself. Any corporation organized and legally existing prior to October 1, 1945, by virtue of the provisions of this chapter may, by a vote as required by its charter and bylaws and the laws of the state, amend its certificate of incorporation for the purpose of exercising the powers and provisions of this chapter relating to the purchase and selling or supplying to its members of surplus materials, including federal materials, machinery and demountable housing units, or other machinery, equipment or supplies.