http://algaescrubber.net
Check out the new one that just got released a week ago. You don't need a fancy box anymore or even a water pump. Now all you need is an air pump, air stone, some zip ties, white mesh screen (from Michael's) and a light.
Reefwars, how old is the one you built? They re-did the sizing guidelines. The size was changed to being based on how much you feed, not the size of the tank. In the end, most scrubbers are a lot smaller now.
Ruglu6, that looks like a horizontal scrubber. They work ok... A vertical scrubber is much more effective though.