2in RC Airplane Wheel
This is a fairly simple design to replace the spoked hub of this (http://www.hobbyking.com/hobbyking/store/__9832__Super_Light_Multi_Spoke_Wheel_D50x13mm_5pcs_bag_.html) 2in (50mm) wheel on my Hobby King Yak 54.
It takes a M3 axle but doesn't require any threading.
I included two versions. V3 is offset to the edge of the rim, and V2 has almost no offset. I am using the automotive definition of offset where zero offset is at on the centerline of the wheel and positive offset pushes the wheel outward and negative goes the other way.
I part in the picture on the airplane was printed in ABS with about 25% infill and I have a number of flights on it. I think you can probably go with 10-15% infill and it will be fine.