I am building the frame for the ARM board out of balsa wood. I also decided to make it an octocopter. (Originally I was planning on a hex, but then the ebay seller who I bought the motors from decided to send me 7mm ones instead of 8.5mm... I figured that with the smaller, weaker motors, that I would be more likely to have sufficient lifting power if I threw a whole lot of motors at the problem.)
I still wanted to keep things small, so I am trying for a 160mm motor to motor build. 4 motors are in the corners, 4 are in between the corner ones (think of a + and x quad copfiguration stuck on top of each other).
The motor mounts are hickory, drilled out and glued on to the balsa frame.
The frame plus 8 motor mounts and roll cage is 16g. 8 motors plus props are 34g. The control board plus sensors is about 9g. The battery is about 12g. Unless I forgot something, this should make a flight weight of about 71g (this is compared to the quad weight of 57g, including the wire roll cage). I am hoping that the 8 motors (albeit weaker) will give me enough payload capacity to put a micro camera on board.
Some pictures of my progress are below.