A Denford CNC milling 20mm 1.5mm Alu square tubing from B&Q. I've milled a load of holes in the arms to reduce weight and a large hole is being cut in this video for the esc/motor cables to be routed through. I want to keep all cables within the frame.
I built a tricopter but it's a little large so I'm now going for a smaller quad made from 20mm alu square tube. Electronics are arduino pro mini 16mhz, wii + and nunchuck for accelerometer and gyros & a paris 4 board which everything is soldered into.