Such a cool topic and printing! What printer do you have? Time I looked into that 
Prusa Mini. It’s currently printing side-panels for my 5" build.
BTW, conclusion is that the PolyPropylene seems to break a fair amount. I’m constantly improving the designs to be more resilient as different parts break. It is getting to the stage that the most common part to break is the nylon standoffs I’ve been using, so I’m going to switch to aluminium.
The other issue is flex in the arms. On the 2" this is not too much of a problem and it still flies really well especially since I removed the prop guards. On the 3" the bend and twist on the arms does cause some issues.
However I upped the extrusion rate in the printer by 10% and I’m getting more resilient prints now.
Here is the 2" as it looks now after the latest iteration.
The 3" is still basically the same as it was in that last photo, but with added LEDs.
Looks like good fun though, and playing and experimenting.
Am tempted by a 3D printer, and just came across the mini. Will give it a little while longer before making a decision.