Circumference: 16[17.5, 19.5, 20.5, 23] inches

Mission Falls 1824 Cotton [100% Cotton; 84yd/77 m per 50g skein]; 1 skein each color
[MC] #401 Slate Blue
[CC] #100 Black

Recommended needle size:
1 set US #7/4.5mm double-point needles
1 set US #5/3.75mm double-point needles
[always use a needle size that gives you the gauge listed below -- every knitter's gauge is unique]

Crochet hook
1 package flat sewing elastic, 3/8 inch wide
Sewing needle and thread
Split ring marker or safety pin
Waste yarn
Tapestry needle

18 sts/26 rows = 4 inches in stockinette st using larger needles

Stripe Pattern:
Work 4 rounds CC.
Work 4 rounds MC.
Repeat these 8 rounds for Stripe Pattern.

Crochet Cast On
Using waste yarn, work a crochet chain several sts longer than the number of sts to be cast on. Starting 1 or 2 sts in from end of chain and using working yarn, pick up and k 1 st in the back loop of each ch until the required number of sts have been picked up. Later, the chain will be unraveled and the resulting live sts picked up.

Instructions for grafting can be found here.

Band
Before casting on, prepare elastic as follows:
Loop elastic around head of wearer so that it sits where lower edge of hat will be when worn.
Tighten it so that it is snug but comfortable, and mark its length.
Sew securely into a loop, with ends overlapping approx. 1 inch.
Trim excess length.

With smaller needles and MC, CO 72[80, 88, 96, 104] sts using Crochet Cast On. Be sure to begin picking up sts at the end of the crochet chain, instead of the beginning. Divide sts evenly between needles and join to begin working in the round, being careful not to twist. Place marker or pin in work to indicate beginning of round.

K 7 rounds.
Switch to larger needles and k 8 rounds.

Hold loop of elastic against WS of work, just below sts on needle. Fold work in half to WS around elastic, so that CO edge is directly behind sts on needle.

As you work the joining round below, remove the crochet chain from a few sts of the CO edge at a time, placing them on a smaller double-point needle.

Crown
Join CC. Work 6[8, 10, 12, 14] rounds in Stripe Pattern.

Continuing in Stripe Pattern, shape crown as follows, beginning on Round 9[7, 5, 3, 1]:

Round 1: [K2tog, k11] to end. -[-, -, -, 96] sts.
Even-Numbered Rounds 2-22: K all sts.
Round 3: [K2tog, k10] to end. -[-, -, 88, 88] sts.
Round 5: [K2tog, k9] to end. -[-, 80, 80, 80] sts.
Round 7: [K2tog, k8] to end. -[72, 72, 72, 72] sts.
Round 9: [K2tog, k7] to end. 64 sts.
Round 11: [K2tog, k6] to end. 56 sts.
Round 13: [K2tog, k5] to end. 48 sts.
Round 15: [K2tog, k4] to end. 40 sts.
Round 17: [K2tog, k3] to end. 32 sts.
Round 19: [K2tog, k2] to end. 24 sts.
Round 21: [K2tog, k1] to end. 16 sts.
Round 23: [K2tog] to end. 8 sts. Break MC.

Propellor
Using smaller needles and CC, k 3 rounds.
Next Round: [K1, m1, k2, m1, k1] twice. 12 sts.
Next Round: [K2, m1, k2, m1, k2] twice. 16 sts.
Slip first 8 sts to waste yarn.

Propellor Blade
Divide remaining 8 sts between needles and join to continue working in the round.
Round 1: K all sts.
Round 2: [K1, m1, k2, m1, k1] twice. 12 sts.
Round 3: K all sts.
Round 4: [K1, m1, k4, m1, k1] twice. 16 sts.
Rounds 5-14: K all sts.
Round 15: [K1, k2tog, k4, ssk, k1] twice. 12 sts.
Round 16: [K1, k2tog, k2, ssk, k1] twice. 8 sts.
Slip first 4 sts to one needle and last 4 sts to a second neede. Graft sts on first needle to sts on second needle.

Place held sts on needles and rejoin CC. Work second blade in same way as first.

Daniel Yuhas lives in Brooklyn, but has his eye on a solar-powered hover-castle. 

He chronicles his crafting adventures at tattingmydoilies.com.