http://www.instructables.com/id/ELEV-8/
Step 6:
After screwing on the black landing gear and each boom assembly is complete, move onto the main frame (Assembly Diagrams, page 3). This is a simple step—just a few
spacers!
After attaching the 4 spacers, set the top frame aside for later.
Step 7:
Now refer to page 4 of the Assembly Diagrams, but don't install the top frame yet! Before that, attach each boom assembly to the bottom frame and start organizing your
wires. I think you'll find that keeping the wiring neat is a real challenge on any multi-rotor build you do, so it's always a good idea to start organizing as soon as you can.