It's a simple and useful instructables. If you have more then one knife in your drawer, you might need this if you want to keep your edge sharp. You can also use a knife block, but I don't like this alternative because it take to much space on my workspace.
Step 1: Materials and tools
-Knife that need a new sheath
-Old box of frozen pizza (or any other kind of cardboard)
-Pen or pencil
-Rulers or measuring tape (rulers work best)
Step 2: Trace your blade
After that, you add another rectangle of the same size over the first.
To complete, you add a third rectangle the same length of the blade but only 1/2" high over the last rectangle and a last rectangle the height of the blade on the side of the first rectangle.
If it's not clear, just look at the picture, they will explain it better than me (a picture is worth a thousand words).
Step 3: Cutting
Again this time, the picture make it clear.
Step 4: Folding
You start by folding the second big rectangle over the first.
After you can fold the two last rectangle over to make something like a box with only one opening.