This is my self-built CD rack. It consists of two wooden boards, two steel feet, 18 640x10mm aluminium rods with threaded ends and lots of nuts, washers and bolts. It's 125cm high (130cm with CDs) and has space for up to 336 CDs.

Heavy steel feet lower the center of gravity and prevent the rack from tumbling.

Closeup view of rods connected to a board. Some may find the nuts and washers a little crude, but I like the technical look.

Side view.

One good thing about the three-rod-configuration is that the CDs can be placed
in two positions. This is good for marking empty CD cases if the CD is in the
CD player or for marking borrowed CDs.
The rods are also superior to "single-slot-racks" if you buy a new
CD and try to put it between two CDs. The only problem is that it's easy to
knock a CD over.