One Shoulder Cut Out Long Prom Dress with Side Sash Pink 4 Prom Dress Alterations: Get Ready to Shine on Prom Night! Your prom dress should fit you perfectly and feel as special as the night itself. Professional alterations can make sure your No Sew Fashion Hack for Long Dresses Help!! Prom gown too long, want to hem by hand. : r InvisibleMending Easy way to hem a prom dress. Its easier than cutting first. You sew first. , mark the hem. Subtract 1 2 for hem. , mark with chalk marker and turn to the inside on chalk marks. I hemmed 2 Metallic Cut Out Long Prom Dress with Beads Gold 2