Without the 12mm needles called for, I subbed in 10mm and it seemed to work out nicely.
The pattern is a variation on the typical, triangular, garter stitch, dish-cloth- style shawlette. This pattern starts with 10 stitches. In Row 3, those stitches are doubled, then in row 5 they are increased by 33%. After that there is a increase at each end of every row.
You cast off when you run out of yarn or you can't stand it any longer. And my trick for a loose enough cast-off is to do a KF&B every tenth stitch in the row preceding the cast off row. This increases the stitch count by 10% making for a nice, loose, cast-off edge.
My ACRYLIC!! 'just for fun' shawlette is either a dust cloth
an artistic, stylish topper for my black coat.