Attribution:http://www.thingiverse.com/thing:40475 - Original feethttp://www.thingiverse.com/thing:10541 - pinsFoot for quadcopters made from 13mm square tubing with a predrilled hole on the side of the tubing for mounting a foot.  Meant for my [Hobbyking X525](http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=22800&aff=1090853).  The v2 version is stronger, mine (printed in ABS) survived a few hard landings without damage. Uses same pin as original. v2 also have indentations for the motor mount bolts as present on the X525.  Pin fits in hole at the bottom of the foot.