The Copper Rack Idea came to me after watching a plumber hookup my additional bathroom in the attic.
First, count all your CDs.
Second, pick the area of your wall that's most convenient.
Third, decide what the perfect rack Width would be for that wall.
Fourth, decide how much extra space you desire for future purchases.
I like to be conservative and use .395" Width per CD.
This would give you approximately 30 CDs per Foot.