Shown with a cast-on count of 27 stitches.  

• Rows 1 and 9 (RS): *[K3, p1] twice, k1, p1, repeat from * to last 7 sts, k3, p1, k3.
• Rows 2 and 10: *[P3, k1] twice, p1, k1, repeat from * to last 7 sts, p3, k1, p3.
• Rows 3 and 7: K2, p1, k1, p1, *[k3, p1] twice, k1, p1, repeat from * to last 2 sts, k2.
• Rows 4 and 8: P2, k1, p1, k1, *[p3, k1] twice, p1, k1, repeat from * to last 2 sts, p2.
• Row 5: [K1, p1] 3 times, *[k2, p1] twice, [k1, p1] twice, repeat from * to last st, k1.
• Row 6: [P1, k1] 3 times, *[p2, k1] twice, [p1, k1] twice, repeat from * to last st, p1.
• Row 11: K3, p1, *k2, [p1, k1] twice, p1, k2, p1, repeat from * to last 3 sts, k3.
• Row 12: P3, k1, *p2, [k1, p1] twice, k1, p2, k1, repeat from * to last 3 sts, p3.
• Repeat rows 1-12.