Step 1: Measure the length, width, and height of the box you want to make a separator for.
Step 2: Cut out two pieces of cardboard. both should have the same height as your box, and cut one to be as long as the width of your box, and the other as long as the length of your box.
Step 3: Since you are not a very good cutter, and since cardboard is ugly, cover them in some pretty paper.
Step 4: Cut a slit in each piece, right in the center, half way through.
Step 5: Slide the pieces together at the slits. Put them so that the cuts you made are touching, and then push hard to get them together.
Step 6: Put them in the box and organize your stuff. You may have to cut them down a tiny bit to get them to fit.
Step 7: Organize your stuff!