This is a simple box that is convenient for many purposes. The box works best when the sides are at least 1 inch (2.54 cm) tall.

Tools:

ruler
pencil
utility knife or scalpel
cutting mat
bone folder (or horn or Teflon folder) to score the creases
binder clips, Boston/Bulldog clips, or clothes pins

Supplies:

corrugated cardboard (acid-free, lignin free board is best)
adhesive (polyvyinyl acetate [PVA] white glue is practical; I used Jade 711)
waste paper (to protect work surface from glue)
small scraps of blotter matboard (to cushion the clips and prevent them from making dents in the box)

Step 1: Mark the Board With a Pencil and Ruler

Remember to make the "lid" a bit larger than the bottom "tray" (the thickness of two boards)

Remember to measure the contents of the box at the largest point (don't assume that the contents are a perfect square or rectangle)

Step 2: Cut the Corner Flaps

Remove a thin strip of board (the thickness of one board) the make cleaner corners

Cut the "lid" flaps with the grain and the bottom "tray" flaps against the grain

( "lid" flaps will be folded against the grain, while the "tray" flaps will be folded along the grain)

Step 3: Cut the Marked Section

Rounded corners at the rear of the "lid" will make it easier to open and close the box, but the rounding is optional.

Step 4: Crease the Board

Use a ruler and a bone folder to crease the board, forming the side walls of the box.

Step 5: Test the Creases

Fold all of the crease lines to ensure that the box will open and close correctly

Step 6: Split the Corners (option 1)

Split the corners and remove one facing paper layer, revealing the corrugation. The corrugated surface will be where you can apply your glue.

Check option 2 before deciding whether to use this style of corner.

Step 7: Split the Corners (option 2)

Split the board and remove a bit of the corrugated core to make cleaner, more compact corners.

If you leave the corner flaps without splitting them then you will need to account for the extra thickness by making the lower "tray" of the box smaller than the "lid" by the thickness of two boards.