This free pattern originally published in:
Woolco Knitting & Crocheting Manual 
MATERIAL-4 skeins of color Woolco Germantown Zephyr. 3 steel needles No. 14. No. 3 ½ Woolco hook. ¾-yard elastic.
Cast on 16 stitches.
1ST AND 2D ROWS-*Knit 2, purl 2.* Repeat across row.
3D AND 4TH ROWS-*Purl 2, knit 2.*