This is the 4th revision quadcopter I've designed - versions 2 and 3 are not worthy to be uploaded. (If you must know, version 2 was to be just version 1 with metal arms instead of 3d printed, and version 3 was a complete sheet metal based quadcopter) This quadcopter has metal arms (for strength), but 3d printed Motor mounts, propeller cages, battery and camera mount, and landing gear. The landing gear is spring loaded for softer landings. The propeller cage is not mount for crash protection, it was designed more as a marker for indoor flying to know where the propeller is. That being said, it will survive light bumps. This quadcopter was designed to use DT-750 motors (the hole mounting pattern on the motor mount is for the DT 750) and a KK (or other square mounting hole pattern) board, though it can be easily modified to accomodate other boards and motors. From one end of the cage to the other, it is around 29 inches. There is a space on the front of the bottom center piece that allows for easy attachment of other items (camera, sensor, etc). Happy flying!