This design is a very simple tube, knitted in bulky yarn that will warm your ass nicely.
First you knit top-down stockinette in gradient stripes (alternating colors) using the bulky yarn. Then you add waist ribbing in a lighter yarn using thinner needles for fit and holding up.

You can easily adjust the pattern to fit your hip circumference and yarn weight, so it can be a scrap yarn project. The two bulky colors should have the same weight but the lighter yarn is a more flexible selection.
Yardage distribution:
MC 40%
CC1 50%
CC2 10% (waist ribbing)