For this pattern you can use any yarn and any hook according to the drape and look you would like to obtain.
It is completely made to measure so you will have to take all the measurements at the beginning and do a little math….I promise very easy math.
Remember to take the measurement keeping in mind that a cardi/vest can be used as a layer on top of other garments.

I used
150gr of 4ply for an XS (hook 4.5 and 5.5)
250gr of weight 3 yarn for an M (hook 5 and 6)
400gr of chunky yarn for a L (hook 9 and 10)