This pattern can be done in any size and needles.
I like using # 11 for adult hats (16 sts, total yardage approx 80 yards).
The hat can be done short (up to the ears, about 6.5” tall),
or ‘cover all/cancer hat’ (about 8” tall).
Versions include st. st which is faster and more loose
or garter st which takes longer and more sturdy.
You can use 3 to 7 yarns, and if you run out - switch to another yarn or continue without it.
The braid is done as part of the knitting, and in the end - either leave a tail as I did (that’s my knitter-artist statement), or weave the ends in.
Hope you’ll enjoy it, and let me know if you have any difficulties.