Such revenue bonds shall bear interest at not more than twelve percent per annum, payable semiannually, or at shorter intervals, and shall mature at such time or times, not exceeding forty years, as may be determined by the ordinance or ordinances authorizing the issuance of such bonds. Such bonds may be made redeemable before maturity, at the option of the municipality or municipalities issuing the same, to be exercised by said board, at not more than the par value thereof, and at a premium of not more than five percent, under such terms and conditions as may be fixed by the ordinance or ordinances authorizing the issuance of the bonds. The principal and interest of the bonds may be made payable in any lawful medium. Such ordinance or ordinances shall determine the form of the bonds, either coupon or registered, shall set forth any registration or conversion privileges, and shall fix the denomination or denominations of such bonds, and the place or places of the payment of the principal and interest thereof, which may be at any banking institution or trust company within or without the state. When two or more municipalities take joint action under the provisions of this article, the bonds shall be issued by the participating municipalities either as separate or joint bonds, as the governing bodies thereof may agree, and when separate bonds are issued, the amount of the bonds to be issued by each participating municipality shall be fixed by agreement of the governing bodies of the participating municipalities set forth in the ordinance of each participating municipality authorizing the issuance of such bonds. The bonds shall contain a statement on their face that the municipality or municipalities issuing the same shall not be obligated to pay the same, or the interest thereon, except from the special fund derived from the net revenue of the works, or the pro rata part thereof, as provided for in section eleven hereof. All such bonds shall be, and shall have and are hereby declared to have all the qualities and incidents of negotiable instruments, under the Uniform Commercial Code of this state. The bonds shall be executed in such manner as the governing body or bodies may direct. The bonds shall be sold by the governing body or bodies in such manner as may be determined to be for the best interest of the municipality or municipalities: Provided, That said bonds shall not be negotiated at a price lower than a price which when computed to maturity upon standard tables of bond values will show a net return of more than thirteen percent per annum to the purchaser upon the amount paid therefor. Any surplus of the bond proceeds over and above the cost of the project shall be paid into the sinking fund hereinafter provided for. If the proceeds of the bonds, by error of calculation or otherwise, shall be less than the cost of the project, additional bonds may in like manner be issued to provide the amount of such deficit, and, unless otherwise provided in the ordinance or ordinances authorizing the issuance of the bonds first issued, or in the trust indenture hereinafter authorized, shall be deemed to be of same issue, and shall be entitled to payment without preference or priority of the bonds first issued; and if any preference or priority of the bonds first issued is provided for in the ordinance or ordinances authorizing the issuance of the bonds first issued or in said trust indenture, such preference or priority shall not extend to an amount exceeding ten percent of the original issue. Prior to the preparation of the definitive bonds, interim certificates may, under like restrictions, be issued, exchangeable for definitive bonds upon the issuance of the latter.