Good luck finding actual plans for them online, there aren't many. Most are constructed with an individual aquarist's setup in mind.
If you are looking to do something like this let me know;
http
/www.angelsonly.com/hatchery.htm I'm pretty sure I can come up with plans for those racks.
If you are looking to do something smaller, take a look through these pics, tell me what size (lxwxh) tanks you have & how many
http
/www.fishforums.net/content/forum/20.../Fishroom-Tour/
I have a pretty good assortment of racks for 10's, 20's, 29's, 55's, as well as 2.5 & 5 gallon setups. Your physical attributes have to be taken into account when building racks, as well as ceiling height. I'm 6', 215#, someone 5'2" would have trouble with those top tanks, while someone 315# would have trouble squeezing between the rack for lower tanks.
Here's some really craptacular drawings I did some time ago for someone, these will hold three 20 longs or 29's, and are pretty much how most of my racks are built;
They're built with pressure treated 2x4's, & 3" deck screws.
Here's the latest rack, I'm just finishing running electric & air today;