Let’s just say — hypothetically — that if one were making a new lightweight coat from the retro 1940s Butterick pattern out of cotton velvet and lined with china silk, but being very naughty and not blogging it because one was tired and just needed to crank it out so one would have a coat to wear this winter, would one want to interline it (for shaping purposes, not warmth)? And (again, hypothetically) if so, with what?