This cardigan is made with two hexagons. It comes in sizes from baby to adult.

My example was made using dk / weight 3 yarn but this cardigan can be made with any weight yarn and hook as it is made to measure.

Materials
I used Dk / weight 3 yarn for my example and have provided approx amount of yarn for this weight yarn only
3.5mm and 4.5mm crochet hooks or hook preferred for your choice of yarn
3-5 x 15-20mm buttons (if you want to use)

Written in English US terms with abbreviations for UK

Gauge is not necessary as it is made to measure but this is what I got when making mine with weight 3 yarn.

With 4.5mm hook
Row 1: Ch11, dc in fourth chain from hook, dc to end. (8)
Row 2-4: ch1, dc in same, dc to end. (8)

Square should measure 2”

The pdf is 17 pages with plenty of photos.