Some deviations from the original pattern/improvements:
1) two colour long-tail cast-on; it allows you to start the first row of blocks right from the edge of the cap;
2) the first row of the purl blocks is knit rather than purled; thus you avoid a row of tiny speckles that forms if you change a colour at a purl row;
3) used the blocks throughout the cap; in my opinion, it increases integrity of the cap.

I used yarn residues, so the ends had to be woven in on the wrong side. If you use solid/virgin yarn (with no knots/ends); the wrong side also looks interesting & neat, and the cap may be worn inside out.

An (earlier) twin cap_45a building blocks (yellow).