This base is one of the most widely used in origami. It is the starting point for a wide range of models, including flowers, boxes, spinners, some animal models, ornaments, and the list goes on. The waterbomb base has a triangular form when placed flat, as opposed to the square or preliminary base, which has a square or diamond shape. Viewed as a three-dimensional shape or when held in one's hand, for example, the waterbomb base reminds one of a Christmas tree, with 4 branches extending outwards from the central point.

The instructions below are just one method of folding the waterbomb base.

For other methods of folding this and other origami bases, see this page:

Introduction to Folds and Bases Used in Origami        

To fold the waterbomb or balloon base:

1. Position a square of paper on your work surface so that its edges are facing up and down, left and right.  

2. Bring the left edge over to meet the right edge. Crease and unfold. 

3. Bring the top edge down to meet the bottom edge. Crease and unfold.  

4. Turn the paper over and position the square so that its points are facing up and down, left and right.

5. Bring the left point over to meet the right point. Crease and unfold. 

6. Bring the top point down to meet the bottom point. Crease and leave folded. 

7. Grasp the resulting triangle at its left and right sides and push inward. The folds you made previously should allow the model to collapse into a triangular shape with one folded flap sticking out towards the front of the model and one sticking out towards the back.  

8. Fold the front flap to the left and fold the back flap to the right so that your model will lie flat. The model will have one open end.