You have to salvage the battery contacts from the stock AA holder but no soldering is required. I did however have to solder a bump on the + end of each contact because I have flat top batteries.
I've printed and installed this three time already, on my own QX7 and two others for my friends. Installation is not hard but requires patience.
You can try printing without supports if you have a well tuned printer. If you use supports, you have to be careful not to break the thin parts near the battery contacts while removing supports. In order to remove the battery contacts from the AA holder, you may have to cut the plastic or de-solder the contacts. You will have to use a knife to cut any extraneous material that gets in the space for the contacts and it can be difficult to push the metal into place.