You know if you are just looking to build a fun laser; Consider that Green is the most visible color to the Human eye. It is 10-20x more visible than some of the other laser colors. That means you can build a relatively low power one (BUT STILL DANGEROUS SO KEEP IT AWAY FROM EYES) and still be amazed at how bright it is. Even a 5mW green laser looks exceptionally bright. If you insist on making what you want instead... no one can stop you. So I can only suggest that you read safety, read instructions, talk to members with experience, read safety again, read your countries laws that send you to a federal pound me in the butt prison for hitting an airplane, and read safety again. If its not worth taking your time, its not worth doing.