EDIT JULY 2014
For a lacy version (blue tam in second photo) using sock yarn and US 4 needles, instructions have been added to the pattern’s webpage.
EDIT MARCH 2014:
Please consider using fingering or sport weight and size US 4-5 needles rather than my originally recommended DK weight + US 6 for a closer-fitting hat. I have changed the recommended needle size and yarn weight on this page to reflect this. My most sincere apologies to those with too-large hats!!
A Triangles Tam to echo the Triangles! cowl, in a festive colour to match the season :)
The triangles have been downsized to a 6-stitch repeat and the shaping is disguised by taking place during purl rows only.
This was knit according to my own noggin’s size (24”). To make a larger or smaller hat, make sure to add or subtact by groups of 6 stitches so that the triangle chart can be worked as written.