The Hobbyking FPV250 plastic frame isn't the greatest for mounting the flight controller on and maintaining clean wiring.
This bracket mounts with the normal hole spacing, allows for the flight controller (NanoWii in my case) to mount to the top, and for speed controller wiring, receiver and bluetooth module to be hidden underneath.
It all fits under the main protection bracket piece. I used double sided tape to mount the NanoWii to the bracket.

Printed at 0.14mm layer heights, 35mm/sec on a Prussia i3.
Some minor support structure might be needed under the main platform to help it hold up. I didn't need to because my printer can bridge reasonably well without help.

Use double sided tape to mount the flight controller, and you can drill out the frame holes for M3 sized screws/bolts.