James C. Brett makes Marble Chunky yarn in gorgeous colors. The skein is 200 g and an adult hat takes only 1.85 oz.
This hat is made from MC8.
I made this hat by following the directions but using size 8 needles instead of 10. When the hat measured 19 inches along the brim, I stopped and kitchenered the seam. This is the same yarn but a different colorway. An adult hat from this skein had sharp divisions of color but this size sort of blends from one color to another. This color is MC3.
I've been wanting to try slipstitching with 2 colors and found this pattern. The slipstitching is supposed to extend from the brim to the crown but I stopped early.