In addition to my larger drone, I had a smaller, rc-controlled quad too.
Here are few pictures of it; if someone likes to build an almost indestructible crash-proof frame, this could be one (best?) way to do it which is why I am posting these:
It took me two evenings to build it; the frame is very simple (I was thinking to sell it as a kit with cnc-machined parts but it is so simple anyone could make it with normal tools) and very
durable. I'm almost certain that it can take more damage (and took..) than most (all?) of the frames that are available.. ;-)
It's made of 10x10 mm aluminum, a 5 mm polycarbonate sheet, and nylon/polycarbonate sheets which keep the aluminum tubes together. The materials cost next to nothing and are very durable.
I made it only for aerobatics and fun, from parts that were slightly damaged during the development of the Drone. Such as bent out-of balance motors which fell 400 meters to the ground and so on. And I had a bunch of 3-blade junk GWS propellers that I wanted to get rid of..
Before I dismantled it (the escs went to the Drone with new firmware), I had crashed it very hard, many times. I flew it into tree, dropped few meters, without any damage. I crashed it several times to a frozen ground so that propeller blades and the lid of the electronics compartment were flying in the air, installed new propellers and flew (and crashed) some more. It was not meant to be a stable or expensive platform, it was only made for hard flying with little to none margins, unlike my drone which I don't want to damage.
The board in picture is a KK board from Hobbyking. I like Multiwii more, much more stable and easier to fly with accelerometers, that's why I eventually got rid of it. But the frame could have been more than suitable for the Multiwii boards, too =)
The housing the board is located is a enclosure named "art case" from OKW Germany. It's made of ABS and it can withstand crashing to the frozen ground at high speed without damages..
(If interested, I have still those plastic parts if any measurements or so are needed, or if someone of you is without ability to make parts out of polycarbonate, I could probably machine few of them)