I have a long-standing love of slinkies, hats, and sock yarn. I designed this pattern for yarn that I fell in love with but couldn't bear to put on my feet.
Yarn: 1 skein of Schoppel-Wolle's Zauberball, or any other fingering-weight yarn with long color variegations. I imagine Crystal Palace Mini-Mochi, Noro Kureyon/Silk Garden Sock, and Kauni multicolor would work well, too. You'll need 400-500 yards, depending on how slouchy you want your hat to be.
Needles: Size 3 16" circular, size 4 16" circular, set of DPNs in size 4.
Notions: One round stitch marker.
Gauge: 28 stitches and 40 rows = 10 cm or 4 in.
Finished Size: Approximately 23 inches around, but can be blocked wider if desired.
Cast on 160 stitches using smaller needle (preferably long-tail or tubular; the cast-on edge needs to be stretchy!). Place marker to mark the beginning of the row. Slip marker on all rows.
Work in k2, p2 rib, twisting all purl stitches, for four inches (forty rows).
Switch to larger needle.
Purl five rows.
Knit five rows.
Repeat knit and purl sections until hat is desired length, ending with a purl section.
Switch to DPNs for decrease rows:
Round 1: K 9, K2tog around. (144 st.)
Round 2: K around.
Round 3: K 8, K2tog around. (128 st.)
Round 4: K around.
Round 5: K 7, K2tog around. (112 st.)
Round 6: K around.
Round 7: K 6, K2tog around. (96 st.)
Round 8: K around.
Round 9: K 5, K2tog around. (80 st.)
Round 10: K around.
Round 11: K 4, K2tog around. (64 st.)
Round 12: K around.
Round 13: K 3, K2tog around. (48 st.)
Round 14: K around.
Round 15: K2, K2tog around. (32 st.)
Round 16: K around.
Round 17: K1, K2tog around. (16 st.)
Round 18: K around.
Round 19: K2tog around. (8 st.)
Fasten off. Weave in ends. Block to desired dimensions.