The idea was a bit strange in Yujia's mind, but it was an idea that would hopefully work well enough.
First, she would gather the materials needed to make a down jacket: goose down and quality satin cloth. Then, in a quilting manner, she would sew pockets of the down insulation, similar to creating a long blanket. Once she had that finished, she would encase the material within two layers of thick fabric on the outside. That would mask the peculiar and puffy look of the down insulation, making it seem just like any other fur-lined cloak. Embroidery and fur decoration could also be added.
When she had all of those steps completed, wouldn't she be able to make a down jacket in the form of an innocuous cloak? It would be light-weight yet warming, certainly something Zixu could use to stay warm in the winter.