This is my project to make sturdy 3d-printed arms, witch have a length of 400mm. With more arm length the copter will be more stable in the air. This design include 2 separate arms connected with 2 bolts and nuts. In case of a bad crash with damage to one of the arms you just print out the piece that you need. Let me know what your thoughts are with this design. Its already printable, but i am thinking of separate 'legs' which absorb the landing and easily snap off when you hit the ground too hard. Separate legs will reduce the amount of damage on the arms, but are another 4/8 parts you need. What you think about that? UPDATE 21-02-2014 Added a arm for mounting on the DJI base plate UPDATE 18-02-2014 Updated the normal 'Arm 1' because of a faulty bolt pattern. UPDATE 14-02-2014 Added arms with motor mount holes for Tiger MN3510, one with leg and one whitout, also the other arm without legPrint both arms with at least 50% infill to make them sturdy and durable. You'll need 2 bolts and nuts (to connect the arm parts), M4 with at least 40mm lenght.