Cut a DIN A4 Paper in half (1:2.8) Fold the edge down. Fold in the middle and unfold. Check out where the open part is. Fold up shortly before the middle-crease. Repeat on the left. Here must be a gap! Fold the corners inside as shown. valleyfold along this line repeat on the other side turn over fold this edge to this edge repeat on the left fold at the drawn lines alternating mountain and valley folds (pleat) straigt line: mountain fold, dashed line: valley fold. you can vary the position of the pleats if you like cure the edge behind a little bit curve here as well fold this corner behind repeat on the other side I forgot to fold the left corner behind. Of course you have to do this. open the tip of the heart blow up the heart that’s it!