A joint industrial farm and workhouse shall employ the inmates committed or transferred thereto in work on or about the buildings and farm and in growing produce, raising stock, etc., for supplies for its own use, the use of the several city and county or county correctional institutions in the district, any political division thereof or any public or charitable institution owned or managed and directed by the counties constituting the district or any political division thereof. Inmates may also be employed in the preparation of road material, in making brick, tile and concrete or other road building material and in the manufacture of other products and materials as may be found practicable for the use of any of the counties constituting the district and for the proper and healthful employment of the inmates.