This was my first Mugi style attempt and it took me about five hours including the time to photograph, expect a 10 hour commitment over a few days though. I've since added tape to the bottom of the model to make it easier to see in the air. The coroplast I used is translucent so LEDs can be added for night flying. It is possible to find all colors of coroplast but watch out for the thickness, get it too thick and it will be heavier and will require a larger model. I used 2mm coroplast I bought from the Mugi people.
If you are interested in Mugi planes check out mugi.co.uk, they are super helpful and cool to deal with. There is also a strong community of friendly people willing to help out with questions you might have. Search for them on Yahoo groups.
This is my first RC plane and although it is hard to fly it's darn near indestructible. I bit it hard from 300 feet and the Mugi stuck nose down in the dirt. It was ready to fly again as soon as I pulled it out of the ground! My first time out I crashed it so many times my motor shaft bent but the plane was fine. Get lots of extra props, they seem to break easily.