The Basic Idea:
The book fold is a kind of valley
fold,
so it is shown by a dashed line.
Sometimes there is an arrow
showing the folding direction.
Fold one flap of the paper to the other side
of the model,
just like turning a page of a book.
The book fold is a kind of valley
fold,
so it is shown by a dashed line.
Sometimes there is an arrow
showing the folding direction.
Fold one flap of the paper to the other side
of the model,
just like turning a page of a book.