I designed the 3D printed parts in a way so that you can wind the dipole Wires and the Coax Wire on the middle Piece.
http://www.thingiverse.com/thing:2257598
You also will need 8 Isolators.
http://www.thingiverse.com/thing:2256546
The Settings of the 3D Prints are not that important.
I have printed my Parts with 20% Infill and it worked fine.
Best Wishes
Hoonse