Inspired by these hats worn in the film Inception. I couldn't find a rib which matched the one on the original hat, so I used my favourite, 4x4. The weight of the yarn is also much heavier.
The yarn I used is listed as being super bulky, but it's much more like aran, so the result isn't as dense as I'd have liked.
Yarn: Any superbulky. I used 65g/72m of Cortina Soft by Gjestal
Needles: 6mm and 8mm, DPN or 100cm (or longer) long circular for magic loop knitting.
Using 6mm needles and super bulky yarn, CO 56 stistches.
K4, P4 until work measures 12-14 cms.
Switch to 8mm needles and knit until work measures 21 cms.
Shape the crown:
Place a distinctive marker to mark the beginning of the round,
K14, place marker, repeat until the you have four markers with 14 stitches between each.
Round one: K1, K2tog, knit up to the last 2 stitches before the marker, SSK. (Video tutorial on how to SSK)
Round two: Knit.
Repeat these two rounds until there are 16 stitches left, 4 between each marker.
8 stitches left, finish the hat.
Finishing the hat:
Cut the yarn, leaving a tail of about 20cms.
Thread the tail onto a darning/tapestry needle and slip each stitch onto the needle.
Pull tight and finish. (Video tutorial on finishing a hat.)