This vest is a copy of one I made for little girls. Very easy to knit - top-down, so you are able to adjust the size as you knit.
Choose other yarn and bigger/smaller needles - you get bigger/smaller size.
I use for the first one linen/viscose yarn from ICE - the yarn was on sale, so it is problably sold out by now.
Butyou may use any yarn with a gauge that will fit.