a large, square piece of origami paper

Take a large square piece of coloured paper and fold it in half 4 times to make creases like those in the picture.

NB: make sure you open the square between each fold.

Unfold the paper
and lie it flat.

Fold the square in half as shown in the picture.

This step is tricky!

Pinch the sides inside towards the centre and flatten the front creases out to make a kind of tent.

When you press it flat, it should look like the picture

Take the top layer of each of the bottom corners of the triangle, and fold them up to the top corner, making a square shape in the middle (indicated in yellow).

Turn the triangle over and repeat on the other side.

Fold the side corners of the square so they meet in the middle (as indicated in orange). Turn over and repeat.

This time, fold the top points only downwards (one only indicated in green) so they match up with the side. Repeat on both sides

Now tuck these points securely into the slots. You finished water bomb should look like this. Find the small hole at one end of the bomb. Blow gently to make a "puffy" cube. Fill the bomb with water through this hole. Be careful not to throw it directly at anyone!