How to Fold: Paper accordion

Cut in a straight line like the brown dotted line is showing: 

It should look like this below:

Start to fold a zigzag fold using the side of each heart to mark out where to fold along (first shown below):

Continue to alternate folding each heart:

You can use the sides of the heart to see where to stop the fold as shown below:

The end result should look like this:

You can either cut out the heart shapes following the dotted line (for a cleaner cut) in the above example, or alternatively, keep it folded up and cut along the dotted line in one go:

Cut along the top and bottom dotted lines:

Tidy up the edges of each heart (if desired) to go from this:

To this:

It should look like this at the end: