Used the idea of the slit opening from the “Phone Cosy in Linen Stitch” pattern, and the stripes from “The Doppler Effect Cozy”.

Cast on 32 stitches using the Turkish cast-on. Worked in 3x1 rib for 1 1/2 inches, then cast off the back half of the stitches (on the second round of the 2-round light gray stripe). On the next round, cast them on again using cable cast-on.

Continued until case was large enough for the phone, then kitchenered the ends together.

It looks like I knit about 8 rounds of dark gray before doing the first light gray stripe, and I ended with a dark gray section of 6 rounds.