You can knit flat AND work a single row of contrasting color on double pointed or circular needles. (You can’t do this with sticks.) Think of all the color combos you could have with this technique: drop the yarn last used, then pick up and work the next yarn from whatever edge of the work it’s on. This will work with 2 or more colors of yarn. Keep the yarns that climb up the edges slack enough that they don’t pucker the work.
Again, only dps or circular needles will work here. This technique also works best if your knit and purl rows have the same tension.

Skills needed: cast on, knit, purl and bind off.

Gauge is not important in this pattern. Any block-able yarn/thread will work. Make a swatch to check gauge and appearance.