Use up your stash yarn. Cotton, acrylic, wool. App. yardage
180-240 yards/2 oz. 170-220 m/50g.
Use larger hook (and heavier yarn) for larger size.
In the multicolored vest the diameter of the circle after 8 rounds is 16 cm/6,4”. But I measured this after a bit of wearing and it might have stretched at bit. The blue one measured 14,5/5,8” after 8 rounds.

Sorry about the confusion regarding the word “mussle”. One of my not so good translations :-/ It should have been “shell”.

The english version seems to have some challenges. Give it a try. With the changing colors and patterns mistakes are hard to spot ;-) So just make something up. I’m afraid I don’t have the time nor the skills to go through it. If someone else does it will be highly appreciated.

Thanks for all the nice comments. They are what makes designing for free worthwhile!
I love all your colorfull vests :-)