With 1 strand each of A and B held together, ch 17.
Row 1: Dc in 3rd ch from hook and in each ch across.
Row 2: Ch 1, turn, sc in each st across, cut B after last st, leaving a long tail.
Row 3:With 1 strand of A, ch 1, turn, sc in each st across. Fasten off.
Thread B tail into large-eyed needle. Baste across center of strip, pulling gently to create loose gathers. Fasten off.
Weave in ends.
Glue a magnet to wrong side.