Gotta question for ya????

me and my friend are thinking that we are gonna make an interior mix tee gun for our first run. but what i really need to know is if thats something where i could just go into a hard ware store with like 60 or 70 bucks and just pay for everything and go home and then through it all together?? weve got a hose and a compressor but we need to know if we can just go there and pick up the stuff and make a tee gun.