She already had a folded petal pen from a friend, so she decided on the folded corner style. It is actually a very simple project that doesn't require measuring.
Basically you are going to first wrap the pen with your stem color (start where the cap ends so the tape doesn't bunch up when you put the cap on). You end about an inch from the top. You place it on in one piece lengthwise.
Just eyeball it, cut it to the length and stick it on around the pen.
To start the petals, use the color(s) of choice, and cut a 2" x 2" piece (basically a square) off the roll. Fold the right corner down at 45 degrees to the center point.
You will repeat this over and over until you are happy with the size of the flower. For us that was about 30 petals. To determine the placement of each, just try to stagger the points. We used two colors and alternated them, so we did three of each color per level, spacing the points evenly on each layer and making sure no two petals overlapped identically.
As you can imagine we have a lot of tape now, so I'll be posting a lot of duct tape projects :)