Concept isn't too heavy, but you'll need to be able to come up with an xtal set/pump diode combination to get the power you desire. In practice getting an efficient conversion of 808nm pump diode radiaition to 532nm (green) is a black art. If you purchase an xtal set already made that will make things easier, though it's still a lot of stuff to sort for a first project . Access to a machine shop will definitely help.