Cut the pattern piece from your fabric - I used dark red velvet for this one and striped cotton fabric for my other neckwarmer. If the fabric is lightweight you can use interfacing and/or a layer of fleece to make it sturdy and warm.

The length of your pieces is your neck measurement + 2-3cm (if you don't add this, the neckwarmer will probably have a gap in front because fake fur can be quite thick, so the neckwarmer has to be wider than your neck) + seam allowances.
The width is your own choice, I used 8cm + seam allowandes for the velvet. The fake fur piece should measure 5cm more -> mine was 13cm + seam allowances.

Sew the pieces onto each other on the long edges, right sides facing each other. Leave a little gap on one side (somewhere arount the middle works best) so you can turn the neckwarmer inside out later.

Now you need to pin the short edges to each other - see the full size version of the picture to see how to handle the fake fur, I can't really explain this and the photos of it didn't turn out good.

Mark the middle of the short side and pin the satin ribbon between the outer fabric and the fake fur in this place. The ribbon should be inside the neckwarmer, not outside.

Close the short sides and turn the neckwarmer inside out through the gap you've left before.
Stitch the gap (yes, I mean by hand ^^) and you're done!