An oldie but a goodie, Being a macgeek I fell in love with this idea when I saw it in 2001
and I thought I would revive it for the instructable crowd.
Step 1: First you need a Apple Cube
Step 2: Taking it apart
(you can still use the computer, without the shell)
Step 3: Removing the Upper housing and air filter
leaving the two side panels.
Step 4: Putting in the Tissue Box
Step 5: The Finished Product
And when they start to cry with jealousy you can now hand them a fresh tissue.