Be Warned! - I used only scrap wool. I'm waiting (as usual) on a delivery from Bendigo Woollen Mills, and decided to give it a burl ... And it did work.
Found out various important things, first amongst which is what is probably something that a person with a logical mind would've taken for granted: WHEN YOU'RE KNITTING A MOEBIUS, YOU CAN ONLY KNIT SO MUCH
. Because it fills up the circular needle after a while, if you get my drift ...
I'm looking forward to making one without changing colours, because sewing in the ends is all well and good, and I do it Very Carefully; but the fact is that with all the doubling over of the cowl/scarf to keep the neck warm, them ends is highly likely to start unravelling 'emselves. Keep you posted on that.