I saw this on another site. Nice step by step instructions with pictures.
http://www.groveslam.com/images/downloads/baitpen.pdf

Live bait is the best bait.

That looks pretty fancy.... How many herring do you think will stay alive in there?

Very nice! - They say something like 1.25-1.5 gallons per hearing, that's why my keep-alive is good for 20-24 (the limit)...

Very nice bait pen! Yo Clammer ;)