All expenses in connection with the establishment of area career and technical schools or technical institutes and additions and improvements thereof shall be borne by the school districts participating therein in the proportions agreed on by the respective districts. Any school district not participating in the original establishment of an area career and technical school or technical institute, which later elects to become a participant, shall contribute to the cost of the school an amount agreed on with the then participating districts, and shall make such further annual payments on account of obligations to the State Public School Building Authority or rentals under leases with municipality authorities as shall be agreed on. All property of each area career and technical school or technical institute shall be owned jointly by the several school districts participating in the establishment, maintenance and operation thereof, in the proportion the contribution of each to the cost of acquisition, construction and improvement bears to the total cost.