This is similar to how porcupine balls are done, come back from each end of the arm and go back up from the middle.
As James said you can easily power inject from the middle out to every arm. If you are using 12v pixels back feeding from the end should do it also, I made it to 170 nodes on a strip before I needed to backfeed power, pixels typically need it about 50 or more earlier, but back feeding from the end has worked for me on those too.
Alan