This is a mashup of MikeyB's very popular Crossfire 2 and my own T4 Quadcopter's tubular arms which are a bit more rigid than the originals (see video here). Please refer to MikeyB's quadcopter for excellent instructions and the other parts required. Note: I'd recommend using a 4-in-1 ESC if you want to build this quadcopter. MikeyB's design uses separate ESCs strapped to each arm which is not possible with the tubular arms. A 4-in-1 ESC combines the ESCs with the power distribution board and can be mounted in the center of the frame - very tidy! Oh, and the Sketchup file is included so you can make changes to suit yourself. Check out the whole "T" copter family: I've added a post on the forums over at DIY Drones for discussing and improving these designs. 28 March 2014