I made this Fair Isle beret/tam a few years ago and as it is quite popular with my friends on Ravelry I have written the pattern. I knit in the round with circular needles for the corrugated brim and for charts 1,2,3,4 and for part of the crown. Once it becomes uncomfortable to knit on the circular needle, I then use dpn in size 3.25mm (US size 3, UK size 10).
One 25g ball of 4ply in each shade is sufficient to make the beret/tam. I have charted this pattern and I have included charts which are shaded in the colours I used in the design and also included charts in dark grey/white.
You will also need a tapestry or knitters wool needle for weaving in the ends at the end; a stitch marker or scrap piece of wool in a contrasting shade to assist you identify the beginning and end of rows.
I block (’dress’ is the term I use here in Shetland) the beret/tam after I have gently washed it with a mild wool detergent (or a little bit of shampoo) on a dinner plate and leave it to dry overnight.