How to make a large heart origami envelope (page 10)

 

17. Apply two horizontal "valley-folds" of the step #16.   Prepare to "unfold" two valley-folded crease lines.

18. Unfold two valley-folded crease lines of the step #17.   Prepare to apply two vertical "valley-folds" and then "unfold" .

 

 

 

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