"A plastic ceiling tile meant to cover fluorescent lights, cut down and inserted into a box for organizing and carrying copic markers." But not only for copic it can be used for any other marker or color pencils
Go to your builder& supply (i., Lowe& Home Depot) and buy a plastic grid that goes over a fluorescent light fixture. Cut it down to the size you need (she used a Dremmel). Such a GREAT Idea. (BTW, her Copic tutorials are the bomb.
For Copic Markers - This is a cheap CD holder with a CD case in every other slot! You can take out the paper label and color its spine to match your marker pens, put it back in the CD, and put your markers on the CD shelf.
Ikea cd holder turned into a copic Marker holder. An empty CD case was inserted into every other or every third slot, and the markers stored on top of it. Small labels added to the edge clarify where each color goes. Works with ANY Cd storage tower.