This pattern is written as one-size but the hat circumference is easily adjusted due to repeating charts. You can use 4-7 different colors of yarn as long as they are similar in weight.

Other material:
4mm/US6 circular needle 40 cm/16 inches.
4mm/US6 DPNs for finishing the top.

Yardage for a four-color hat:
MC (gray) 46%
CC1 (light blue) 23%
CC2 (black) 18%
CC3 (dark blue) 13%