All you need is a square of paper ... it must be perfectly square ... the ones I have used for this measure 19.5cm x 19.5cm and make a finished box 7cm x 7cm x 3.5cm.
Start with pattern face down.
Make 2 mountain folds ... fold the paper in half, top to bottom ... open it up again and turn the paper 90 degrees and fold in half again top to bottom.
Using the mountain fold lines as guides, fold the four corners of the paper into its center.
Fold the right edge and the left edge into the center line.
Fold the top edge down and the bottom edge up, as shown below.
Undo the last few steps, till it looks like the one below.
Put your finger behind point A and and bring it forward to make a reverse fold. This triangle that is formed is pointed towards the centre of the large triangle.
Tuck in the flap as shown to form the third side of the box.
Turn it around and repeat the reverse fold on the sides and fold in the flap.
You now have box ... well a tray ... you can either use it as a little dish ...