Materials needed: strong shallow box or box lid, bell wire or string, beads, masking tape, ruler, a piece of cardboard, small hammer, and a nail a little larger in diameter than the wire or string.

Begin by measuring the width of your box or box lid. Decide how many columns of beads you would like on your abacus. The fewer the columns, the smaller the numbers you will be able to calculate. Most abaci have at least nine columns. The calculations on the following pages, will not require the use of more than nine columns.

After making your decision, begin to mark off your columns in regular intervals. Do the same on the opposite side of your box or lid. Then, using a nail and a small hammer, make small holes at each marking. When doing this, place the box on a sturdy object that the nail cannot damage. A scrap piece of wood would work well. If your box is made of a thin material, you could use the point on the tip of a scissors instead of a nail.

Now you are ready to select some beads, Be certain to choose beads that are not too large. If they are too wide, they may interfere with each other. You should have room to fit seven beads in each column with plenty of room left over so that the beads can be moved along the columns. Also be certain the beads can move freely on the wire or string you will be using,

There is a divider between heaven and earth. Measure the width and depth of your box or lid. Cut a piece of cardboard to those measurements. Make the same holes in this piece of cardboard as you did on both sides of the box. Then tape it into place inside the box. Make certain to leave the space of at least three beads in heaven.

The final step is stringing the beads. Feed the string or wire from hole to hole in a zigzag fashion. An example of this is shown in the drawing above. Start in "earth." Feed the wire or string through the first hole. Place five beads on the wire; then feed it through the divider. Feed two more beads onto the wire before bringing it through the hole in "heaven." Follow the same process again in reverse by feeding the wire through the next "heaven" hole. Continue this process until all the columns are complete. Make the string or wire taut before taping it at both ends.