The Rakusu is representative of Buddha's robes that he donned when he began his search for enlightenment. As such, when Zen Buddhist take the precepts and follow Buddha's example, they will prepare a Rakusu for Jukai ceremony.
What I have found most amazing about this process so far is the focus that is required along with the meditative aspect that is reached while in the midst of sewing. Furthermore, there is a great appreciation for the thought and detail that is put into how the garment is designed.
Kojun Kishigami Osho (Dharma Heir of Kodo Sawaki Roshi) has a wonderful lecture on the Zen Road page called "Wrapped in the buddha's robe." In it, he explains the logic of the design beautifully:
As you can see, the central piece is raised, which would allow the water to flow from the center towards the right and left, in the way that mountain water flows into a rice field. To obtain this elevation in the center, the pieces are layered on top of each other.
Furthermore, on this kesa, the measurements of the central piece are double those of the upper piece, indicating the maturing of the wearer’s Buddha-mind. This garment is worn by disciples; it is imbued with the Buddhist teaching and vision of the universe.
The depth and meaning behind this little piece of cloth grows with each stitch. I am looking forward to sewing my Rakusu for Jukai next year and am thankful for all the work Taigu has put forth in preparing the training for us.