I designed this quadcopter frame to be easily printed using PLA, and to fit the motors + board from a Syma X1 quadcopter.

The arms are strangely long, but here's the thing: the Syma X1 circuitry doesn't like flying small frames. You get a lot of wobble if you reduce the dimensions much from the original. So I had to make the arms longer to reduce the wobble. The wobble was killing me.

If you want to access the original parametric design, which would allow you to change dimensions such as motor or board size, it is available from Onshape right here.

I print this using Simplify3D, with a layer height of 0.3 mm in PLA, with about 15% infill.

I've attached the Simplify3D print profile so you can just import that if you use Simplify3D already (you should, it's great). It's the file called "Explo Makerbot 5th Generation Print Settings.fff"