Based on Trellis Lace, and modified as suggested by Nancy Marchant: with k3tog as well as sl1-k2tog-psso, the decrease lines create zig-zags.
Shown with a cast-on count of 21 stitches.
1 2 3 4 5 Horizontal repeats
1 2 3 4 5 Vertical repeats
Swatch photo uploaded by jcbriar