Because I obviously need another hobby and something to race, I decided last year to start building a 250mm sized quadcopter. Initially I wanted to 3D print a frame, but for the amount of time spent and what I was looking to do ended up buying a ZMR250, a nice cheap carbon fiber frame. The complete parts list I settled on for the initial build was:

• ZMR 250 250mm carbon fiber frame
• Team Legit Nucleus PDB w/ voltage regulator
• 4x SunnySky x2204s motors
• 4x KISS ESCs
• CC3D flight controller
• Turnigy 9x Tx and default huge RX module

The ESCs I mounted on the arms instead of setting up spacers and mounting them inboard. I was able to keep all the wires short and solder them in place without putting a lot of stress on the joints. I included some small spacers on the bottom plate to accommodate wires and any other regulators or chips I wanted to store inboard.

The PDB I used was very nice, providing a good 5V source for the flight controller without the need to use an extra voltage regulator. It was nice not having to make my own wiring harness as well. I coated all the open solder connections with liquid electrical tape just in case something came loose while I was flying. Carbon fiber is conductive, so I wanted to avoid starting a fire if possible when I crashed.

All put together the quadcopter weighed just over 500 grams, not too bad really. I would of course need some Velcro to hold the camera and battery in place, but if I could get a modest 4:1 thrust to weight ratio with the Gemfan propellers I knew it would be a lot of fun.