These are so fun to make.

Specs:

Needles: US 1 (2.25 mm) bamboo Profi dpns.  (Love these needles.)

Yarn: Baby Ull leftovers (5 colors).  Could also use Stork for these, or other fingering weight/sock yarn.

Gauge: Somewhere in the neighborhood of 8 sts/inch.

The stockinette heel flap was a new thought to me.  Not sure why I never considered doing that before, but I like it.