Decide how many pockets you want on your file organizer. Multiply the amount of pockets you want by 4 inches, then add an additional 8 inches to get the height of your pocket file.
Measure and cut two pieces of heavy-duty corrugated cardboard, foam project board or chip board to the desired height. The width of your pocket file should be 14 inches, which is more than enough to accommodate standard 12-by-9 1/2-inch size pocket files.
Affix the two boards together, back to back, to double the thickness so staples won't go all the way through.
Cut a piece of plastic from an old table cloth or shower curtain to be slightly longer and wider than your board. Lay the plastic, face-down, on your work surface. Place the board, face-down, on top of the plastic. Fold the edges over and staple the plastic edges to the back of the board. The plastic covering front of the board should have a smooth, even, unwrinkled finish.
Cut one plastic strip so that it is 10-by-16 inches. Cut more plastic strips measuring 8-by-16 inches. You should have one strip per pocket you want in your organizer, with one 2 inches longer than the others.
Affix the first 8-by-16-inch strip to the board, horizontally. Lay it across the board so the top of the strip is 4 inches from the top of the board. Staple along the bottom of the strip, starting in the middle and working your way outward toward the edges. Wrap the side edges around the board, turn the board over and staple them to the back of the board.
Add a second 8-by-16-inch strip so its top edge is 4 inches below the first strip's top edge, so it's overlapping the first pocket by 4 inches. Staple it along the bottom, from the center outward to the edges. Fold over the edge flaps and staple them to the back. Continue this pattern down the board with 8-by-16-inch strips.
Place the last strip measuring 10-by-16 across the bottom of the board, its top edge about 4 inches from the top of the strip above it. Wrap the bottom 2-inch edge around the back of the board and staple it. Wrap the two sides of the plastic around the sides of the board and staple them to the back.
Staple a strip of thick cardboard or a cord to the back upper center of the board so you can hang it on a nail or a hook. Place your file folders in the plastic pockets to organize them.