I made a SOF chamber a few years ago and it works great. I still use it occasionally when my main fermentation chamber is occupied or if I want to ferment something at a different temp.
If you use the round water bottles ( they are a little smaller than a gallon) you can stack 3 on each side.
I made a few slight mods to the design. I used some brass tubing for the dowels instead of the grommets. Much more durable. I also put some white board on the bottom so that it is more durable. Instead of having the whole top removeable I made most of it attached and just have the small part over the ice chambers removeable. Much more sturdy that way.I also put it on a platform with casters to easily move it around.
There are some pics of mine in this thread.