How to Machine Sew Sequin Trim. Sequin trim adds sparkle and fun to a costume, but sewing it on by hand is a time-consuming task. Instead, apply the trim using your sewing machine. Unlike hand-sewing that leaves tiny, nearly invisible stitches on the underside of the sequins and the garment, machine-sewing will create a visible line or lines of thread on top of the sequins. However, this is usually acceptable for most costume applications and often is a welcome trade-off for the time-saving convenience of machine sewing.