This lightweight minimalist Quadcopter frame is designed for pilots, learning to fly or pushing the limits. This frame is meant to be a stable, 50 cm in diameter and uses readily available (North America) inexpensive light and rigid aluminium window screen extrusions for stiffness. The arms push fit tight into a central hub which is sandwiched between two hub plates. There are slots for Velcro battery straps. The universal motor mounts push fit tight into the end of the arms. The spacing for control boards is 45mm on the main hub and 35mm on the flight control deck. To replace the arms simply loosen the bolts clamping the arms and pull them out of the central hub. The push fit design eliminates hardware and makes the frame lighter. The lighter the frame, the longer the flight time. At a length of 23 cm, the arms weigh only 16 grams (0.56 ounces) each. These are the electronics I used with this frame. Again, the objective was to keep everything as light as possible: The hextronik motors where chosen because they are very light, inexpensive and have lots of thrust for their size and weight. I have included a motor mount for this motor that allows you to clamp the motor using its 8mm round shaft housing. You can also use your own motors in combination with the universal motor mount. Wires can be run directly through the motor mounts into the hub if you want to hide them for a clean look. Parts: 1) 4X Aluminium window screen extrusions: New York Wire, Manufacturer Product # 71468 (Most North American Hardware stores). I cut mine to 23 cm for a 50cm motor-motor diameter. At 23 cm, the arms weight about 16 grams (0.56 ounces) each. 2) 4X 3mm socket cap bolts, 6mm long 3) 8X 3mm socket cap bolts 12mm long 4) 4X 3 mm socket cap bolts minimum 15 mm long 5) 16X 3mm nuts, regular (2mm thick) 6) 4X 3mm hex nylon standoffs to mount flight control board (minimum 6mm or longer, your choice) 7) 2X Velcro Lipo battery straps 8) For the Hextronik motor mount: 1X 3mm socket cap bolt, 15 mm long and a 3mm lock nut. The nut is embedded into the motor mount. Assembly: The assembly is simple. Push fit the arms into the central hub. Fasten the central hub to the top hub with the 6mm socket cap bolts. Insert the landing arms into the bottom hub. There is a notch so they don't come out once the the hubs are fastened together. Fasten the bottom hub to the top hub with eight 3mm socket cap bolts and nuts. The top and bottom hubs will have a little bit of clearance to allow for the clamping of the aluminium arms. The nuts can be permanently fastened into the top hub. Push the motor mounts into the ends of the arms. There are four holes into the frame spaced 45mm apart to fasten your flight control board or power distribution board. These will take the 15mm (minimum) socket cap bolts for use with the 3mm hex nylon standoffs. If you are not using a power distribution board use the flight control deck plate and fasten it to the main hub using hex standoffs. The flight control plate has 35 mm spacing for mounting the Multiwii, or other control board. If you want to protect the the control board, you can also mount it under the flight control deck plate with standoffs. If you are using the Hextronic motor, or other bell shaped motor with an 8mm shaft housing, you can clamp the motor shaft housing directly into the hextronic motor mount. This combination reduces vibration by bringing the propellors closer to the arms. I have included an .stl file of the aluminium extrusions that will fit this design for reference, as well as an .stl file of the complete assembly. The designs were made with the older parametric CAD version of Cubify Design (3D Systems), also known as Alibre Design.