Step 1:
The popcorn paper is 5,5 bij 5,5 cm or 2x2 inches.

Step 6:
Done.

Step 5:
Make a few more folds if necessary.

Step 2:
Wrap the paper around your finger.

Step 4:
Make a few folds on the open side, so the
model gets more closed.
The folds in this picture are just an example.

Step 3:
Like this.

Step 10:
Prefold in half over this line.

Step 8:
This is an a4 paper with a red lines pattern
printed on.
Valley-fold over these 2 lines.

Step 9:
Mountain-fold over this line.

Step 7:
Make as many popcorn pieces as you want.

Step 16:
Repeat step 15 on the next corner.

Step 15:
First mountain-fold on the upper edge,
then on the edge below.

Step 12:
Prefold over this line, then turn the model.

Step 11:
Prefold the edges to the centerline between the
arrows.

Step 14:

Step 13:
(Pre)fold over these lines. The mountain-folds
are already prefolded.

Step 18:
Make the purple folding lines more sharp.
Then close the box with a little tape, see arrows.

Step 17:
Repeat step 15 on this corner.