its pretty easy to figure out, just a quick study of the pic nanoyed posted will give the important info.
No need to overkill the design either. 1x4 instead of 2x4 will work perfect. Plywood only will work too but a special drill tool would be needed for assembly.
http://reefcentral.com/forums/showthread.php?t=1355576there is a start of MANY stands to get design ideas. Pay close attention to how the stand is framed.
most important part. Get plenty of paper and a ruler and sketch out your design to scale. This will also double as a materials list and construction diagram. I used AutoCAD, went thru 10 or so complete do-overs and took a few months before I was happy with a design that would work and fit my construction abilities.
When you get something put together post it and we can critique it. Take your time to do it right and you'll be appy with the end results.