How to Fold an Origami Secret Envelope

Medium level, 12 steps. From Fun with Paper Folding (Murray and Rigney), 1928. Public domain.

The animated version shows each fold moving, one step per screen. This page shows every step at once.

All 12 steps

Step 1. Start white side up. Fold in half corner to corner, then unfold.
Step 2. Fold in half along the other diagonal, then unfold.
Step 3. Fold the left edge in by one third of the width, then unfold.
Step 4. Fold the right edge in by one third, then unfold.
Step 5. Fold the top edge in by one third, then unfold.
Step 6. Fold the bottom edge in by one third, then unfold. The creases make nine squares.
Step 7. Fold the sides of the middle square up and twist them flat: each edge square folds in half along its diagonal, and the four corners stick out as points.
Step 8. Turn the paper over.
Step 9. Fold the top point down over the middle square.
Step 10. Fold the right point over onto it.
Step 11. Fold the bottom point up over the right one.
Step 12. Fold the left point over the bottom one and tuck its tip under the top point.
Done. The secret envelope (Murray and Rigney, Fun with Paper Folding, 1928). It looks the same on both sides.