over 100 hours but enjoyed doing this very much. all of the glass is the same as the winshield of a car or truck, laminated safety glass. even sprayed it with the latest waterborne ppg auto paint and clear that we had just switched over to at our collision repair center. i sealed all the welds inside and out with fiberglass and urathane sealer. full weatherstripping all over. only air leak is around control levers. next project is a heater with fresh air intake.