If you are looking for a nice way to mount all of your gear onto your multi rotor frame, you should have a look at our new stack up plates. On the product listing you can choose what components you need so that you can create your own stackup.
If you are using AIOP or Multiwii boards with the same 5cm x 5cm footprint then you can also mount the included PDB on the stackup as shown.
You can also use some Vibration Dampers on the stackup for the flight controller.
If you are using an ArduPilot Mega 2.5+ board, then you can mount it as shown, you will also need to use some double sided tape to secure the board down. This is a good idea because it also reduces the vibrations on the board so it will perform better.