I use the pack-it folders for urban travel and love them. Making them with cutting boards and Tyvek sounds like a great idea; you might not even have to do any stitching, just use Tyvek tape to add the piece for the pocket where the "card" is inserted, and use stick-on velcro (or would that work on Tyvek?).
Come to think of it, you probably only need a single cutting board per folder (they usually have 2, one on each side of the clothing stack). One of my pack-its only has one anymore, and it works just fine. That would save on weight too.