Step 1: Mark and cut a large circle
Using a compass, draw the largest circle possible using the entire width of the cardboard. For this project we managed a circle with a diameter of 19 inches (483mm).

Then make a smaller circle with a diameter of 2 inches (50mm) starting from the same center point.

Cut out the large circle.

Step 2: Folding your cardboard circle
Place your cardboard circle on a flat surface. You will be making several folds on this side of the card. First fold your circle in half horizontally. Then make a fold vertically. (This will make a shape of a cross). Line up the folds each time you bend the card to make your folds perfect equal angles from each other.

Now make two more folds in between the spaces, so each fold is 45 degrees.

Next turn your cardboard over and make another four folds (just as you did previously) but in between the last angles.

Your cardboard circle will now have 16 areas, each with 22.5 degree angles. And each inner fold will be followed by an outer fold, giving a concertina effect.