Some designs are just - to me at least - totally simple.
The floppy cap is utterly basic, and it has to be for what it is.

The cap in 'Outlander' is a large soft beret, one disc an inch or so wider than the measurement ear tip to ear tip, and then a ring reducing down to the circumference of the head and a straight band - possibly double with a cord through it - to allow for customer error in measuring and making it slightly big in case it gets put into the washing machine and shrunk a bit.

For extra volume there could be a straight bit between disc and ring - and there is the calculation of the initial felting which will reduce the size from what I knit. Perhaps the challenge of the calculation of the size is enough to make it interesting.

I can't start the knitting now, I have two electronic knitting machines to clean. I already checked their patterning is OK but they are really dirty, and I need to get a spare part too - I'd better get on that, otherwise we'll be waiting for it to arrive before they can be given back and paid for.