Buy a bunch of them. They can be stacked and piled on each other. Using trays and bins is the only way to keep track of small tools, supplies, parts and, projects in progress. You can fold up the drawings/notes/plans and set them in the bottom of a knife's slot, too.
When a commercial company went out of business, I bought a couple hundred blue parts bins. They were between 4" and 10" wide and all are 16" deep. They stack on each other. I keep pretty much everything in them now. All the parts to a project or group of knives go into one bin. No more looking around the shop for where the handle scales for a knife are.