Uppers are fairly straight forward. You will need a barrel nut wrench and a torque wrench. Get an AR armorers tool and a good quality torque wrench, both are highly recommended for barrel and castle nut (lower) install. A set of roll pin punches help but I don't build these all the time so I just used a hammer and an Allen wrench for the roll pins. Also snap ring pliers if you don't get the pre assemble delta pack. Anyone else feel free to add or share what they recommend.