The origami waterbomb base is closely related to the square base. In fact, the only difference is that the mountain folds of the square base are valley folds in the waterbomb base and the valley folds in the square base are mountain folds in the waterbomb base.

To make a waterbomb base:

1. Start with the colored side of your paper face up. Fold in half horizontally.
2. Flip your paper over. Fold in half diagonally. Unfold, then fold in half along the other diagonal.
3. Use the middle horizontal creases to collapse the paper a layered triangle shape.
4. Your waterbomb base is now complete.

The origami balloon is one example of a project that uses the waterbomb base.

To make an origami balloon:

1. Make a waterbomb base.
2. Fold the front left and right flaps to the top of the waterbomb base. Turn the paper over, then fold the back left and right flaps to the top. Your paper will be in the shape of a diamond when you are done.
3. Fold the right and left corners to the center of the diamond. Flip the paper over and repeat this step on the other side.
4. Tuck all four of the loose flaps into the folds you just made. You will need to tuck the paper in as far as it will go, because this is what makes your balloon ready to inflate. The easiest way to do this is to fold the triangles out, then fold them back onto themselves so you have a small triangle that fits neatly into the balloon flap.
5. Blow in to the end of the balloon that has a small hole. You'll end up with a paper cube at first, but it should be a round ball shape when it's fully inflated. If the balloon won't hold air, check to make sure the flaps from the last step are tucked in correctly.
6. You can use your balloon to play a game of catch or string several balloons together to make a pretty paper garland. If desired, you can decorate the balloons with stickers for a festive touch.