Summarize this article:

This pen is going to act as your stem, so look for a pen that doesn't have a clicker on the top or on the side. You want the stem to be smooth and clean. Think about what color you'd like your flower to be when selecting the duct tape. Red, white, and pink are good colors, especially if you want the flower to look like a rose. You will also need a pair of scissors, or a small cutting knife, and a cutting board or a surface where you can cut the duct tape.  Have one to two rolls of duct tape in different colors if you’d like to make a multicolored tape flower pen. Get a small roll of green duct tape for the “stem” and the “leaves” of the flower pen.

Summary:
Pick a pen. Get your duct tape and other supplies.