Origami Coach

Waterbomb

A flat triangular base becomes a small balloon. The tucked flaps are the key: work gently and keep the inflation opening clear.

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Before you begin

1 sheet · Square paper

15 × 15 cm

No scissors needed

This lesson is being checked for folding accuracy. It has not yet passed a physical fold-through review.

Step-by-step instructions

Read through the fold before you begin, or open any step in the folding viewer.

  1. After step 1: The square is flat.

    Prepare your square

    Place the colored side down.

    Look for: The square is flat.

    See this fold
  2. After step 2: A diagonal guide crosses the square.

    Crease the first diagonal

    Fold corner to opposite corner, then open.

    Look for: A diagonal guide crosses the square.

    See this fold
  3. After step 3: The diagonal guides cross in the middle.

    Crease the second diagonal

    Fold the other pair of opposite corners together, then open.

    Look for: The diagonal guides cross in the middle.

    See this fold
  4. After step 4: The horizontal crease bends opposite to the diagonals.

    Turn over and crease in half

    Turn the paper over. Fold edge to opposite edge, then unfold.

    Look for: The horizontal crease bends opposite to the diagonals.

    See this fold
  5. After step 5: The waterbomb base has two flaps on each side.

    Collapse the base

    Bring the left and right midpoints inward. Let the diagonal creases close into a layered triangle.

    Look for: The waterbomb base has two flaps on each side.

    See this fold
  6. After step 6: A diamond appears on the front.

    Lift the front corners

    Fold the two front bottom corners up to the top point.

    Look for: A diamond appears on the front.

    See this fold
  7. After step 7: Both sides have diamond-shaped flaps.

    Repeat on the back

    Turn over and bring the two remaining bottom corners to the top.

    Look for: Both sides have diamond-shaped flaps.

    See this fold
  8. After step 8: Two small pockets lie beside the center line.

    Fold the front side points inward

    Fold the left and right corners of the front diamond to the center.

    Look for: Two small pockets lie beside the center line.

    See this fold
  9. After step 9: Both front tips are held inside pockets.

    Tuck the front tips

    Fold the two loose top tips down and insert each into its neighboring pocket.

    Look for: Both front tips are held inside pockets.

    See this fold
  10. After step 10: All four loose tips are tucked.

    Repeat the pockets behind

    Turn over. Fold the side corners inward and tuck the two remaining top tips into their pockets.

    Look for: All four loose tips are tucked.

    See this fold
  11. After step 11: The flat packet expands into a paper balloon.

    Gently open the form

    Locate the small opening at one end. Ease the layers apart, then gently blow into the opening. The animation simplifies the flexible walls; let your paper round out naturally.

    Look for: The flat packet expands into a paper balloon.

    See this fold