I think this is going to be my prototype, ultimate kids and teens hat: high-contrast stripes of widthwise purl ribs on a stockinette background for depth and warmth, scrunchy and a bit slouchy fit, big needles to keep the acrylic worsted soft.

Mods:
6 rows K3, P1 ribbing
% color change: K one row in stripe color 1
stripe: P 4 rows OR P 5 rows for more of the colors)
background: K 4 rows in main color %
Repeat between % % three times.
Decrease in the color change row.