This jacket design was attributed by my friend to Carter Smith, an American fibre artist who specializes in shibori dying. There's more about him here.
Shibori is a "Japanese term for several methods of dyeing cloth with a pattern by binding, stitching, folding, twisting, compressing it, or capping. Some of these methods are known in the West as tie-dye", to quote Wikipedia.
The jacket design takes advantage of the type of fabric Carter Smith tends to work with - drapey silk with beautiful pattern or surface design. This is because it's made with only two (2) pieces, and each of them is just a big square.
So, do you want to know how to make the jacket?
Instructions for a bias garment like this jacket were published in issue no. 143 of Threads Magazine ("Get biased - create a bias topper from two squares of fabric"). However there is a serious error in the article as published. It said to adjust the size of the smaller square according to your hip measurement - and that the diagonal measurement on the small square should be 1/2 your hip measurement. In the next issue, after several people complained that this made a garment which was much too small, Threads acknowledged that each side of the small square should be 1/2 your hip measurement. (Or, more straightforwardly, each side of the large square should be the same measurement as your hip circumference...) My jacket squares are 40" and 20".
(If you click on the pictures, they should enlarge.)
Sew the right angle of the triangle from one marked point to the other, i.e. leaving the pointy ends unsewn.
At this point you have a fully enclosed thing which is vaguely triangular with a square bottom. To turn it into a wearable garment you have to cut openings at the bottom, sleeve ends, and neck. A front opening is optional since you can make this as a pullover.
This is a different sleeve finishing method than in the Threads article - they want you to just cut the pointy end off. This method makes a neat little gusset instead - it fits better and I think looks better than a batwing shape ending right in the cuff.
Obviously, for a real garment you would, once satisfied, finish all the edges using a narrow rolled hem.