Figuring out how many boards you need...

How does everyone figure out how many sheets of wood they need for their racks? I am wanting to build a small rack (4-5 28qt tub setup with belly heat) but dont really know where to start with planning out my sheets.

I'm about to just go buy a large foam board and construct it with that so I can optimize how many sheets I'd need. Any ideas for planning or plans for a small melamine rack?

what are the measurements of your tubs and how many will you have?
tell me that and i will tell you what you need.
also do you have a router?

Heres my thread with all the dimensions for a 5 tub 28qt rack.

beleive is was 1.5 or 2 sheets of melamine

http://ball-pythons.net/forums/showthread.php?t=101055

Bill, I dont have a router but I do have a dremel tool with a router attachment like thing...

The tub measurments I took from flameethrower's post, 17"x23". Thinking I'll make it a 5 tub rack. I'm wanting to put the tubs in the other way as opposed to how flame did theirs and just needing it to be a cheaper rack until I move... Need more space! Haha.