I'd like to learn how to use an abacus so needed one to practise on.

After searching around for discarded boxes, I found several Mooncake and
old Paint Brush boxes that would make a colourful looking abacus.

This would be a great project for primary-aged children I think to
pique an interest in mathematics by learning in a playful way,
improve their visual memory logical thinking and speed up calculations.

For myself, math used to be a mundane event but since learning abacus, I love it!
One of the most helpful softwares I've come across is AbacusMaster -
which is really helpful for visual learners. It includes a digital abacus to practice
on and you can gain a sound knowledge of the lovely abacus method in
no time at all.

A useful step-by-step book with clear pictures and simple
explanations I'd recommend reading online book by Takashi Kojima, Kamie Markarian
and MathSecret (more info step 7) are interesting for children to pick up abacus quickly.

However if you need to pick up on your calculating speed fast, I recommend reading
Speed Math For Kids: The Fast, Fun Way to Do Calculations by Bill Handley. Read
Speed Math: Secret Skills for Lightning Calculation here

Who needs a calculator when the abacus method is in your memory?

Here's how to make one in few minutes and costing next to nothing!

Step 1: Collect Things to Use

You will need:

Pliers
Thin wire or strong string such as nylon
Empty cardboard box
Beads (or macaroni would work!)
Strong glue
Nail polish / waterproof paint

Step 2: Making the Abacus A

Cut a horizontal piece of cardboard for dividing the "heavenly" and "earthly" beads from each other.
Use strong glue to secure one third of the way in the box.

Cut 13 -21 wires depending on your needs or the size of the box you have.

Collect four beads for each of the "earthly" beads and two beads for the
"heavenly" beads - these are above the central wall.

NB. Some children find it difficult to grasp how one (heavenly)
bead can equal five when they can only see one bead sitting there.

It might help to string a larger bead for the whole upper deck so they
more likely to remember that the bigger bead must be worth a bigger number.

Step 3: Making the Abacus B

Mark your box horizontally at equal distances with a ruler.

To work out the distances between the beads first count the
number of units you wish to place horizontally across the width of the box.

Next measure the width of the box across.
Divide this by the number of wires you chose.

Poke a hole at each marked spot.
Also poke holes after marking the central wall.

Using the narrow-nosed pliers loop one end of each wire in a spiral loop.

Insert through each hole at the bottom of the box.

Step 4: Making the Abacus C

Push the wire through the bottom hole.

Slot in four "earthly" beads.

Push through central wall.

Slot on two "heavenly" beads.

Push through end hole of box. Twist a loop to secure.

Step 5: Ready to Use

I decided to paint the plain wooden-coloured beads with contrasting,
bright colours for differentiating each column.

I used nail polish to colour the beads. The contrasting colours really helps me to keep
each unit more clearly in mind.

Step 6: Updates & Other Types of Abaci

After learning more about abaci, I discovered that I actually needed more
units to complete other types of mathematical sums.

So I rearranged my abacus and added two extra walls and 24 more
wires for units to calculate with.

The colourful jewels really brighten my day.

Next I'm trying out mini abaci using flat "Smartie" like beads and wooden frames to carry around easily.
I think I might use a satay stick to work out the sums on them.

Step 7: Using the Abacus (Useful Videos)

Here is a sample for what you're in for when you beginning to grasp abacus.
I'd aim for accuracy rather than speed - and enjoy the process!

Useful online books includeIntroduction to Abacuswith worksheets by Kimie Markarian for teaching children and a colourful free sample 77-page illustrated workbook by MathSecret for children can be found here.

Another useful set of teaching aids from Wales Ireland can be found here
Teachers will find the black and white worksheets useful with great pictures for children beginning on the abacus here

The Japanese Soroban by Takashi Kajima has a clear explanation to understand the complementary formulas (or 'big friends' and 'little friends' formulas),