If this is your first build, a blade balancer, pitch gauge, and optical tach would all be nice tools to have. I'm not sure if you'll have a lot of use for nut drivers, but they are nice to have. If there is a lot of metal to metal fasteners I would pick up some locktite and don't forget some triflow or other lubricant. For allen drivers 1.5, 2, 2.5, and 3 mm do about anything on all of my helis. If you need one a glow plug extension would be a good idea too. I know I didn't cover everything but this should get you going.