To buy: Wacoal Red Carpet Convertible Strapless Bra (available in sizes 32 C to 38H, in three colors), $65; nordstrom.com. To buy: Fashion Forms Go Bare self-adhesive backless strapless bra (available in sizes A through DDD, in two colors), $25; net-a-porter.com. To buy: Fine Lines Plunge 4-Way Convertible Shortline Bra (available in sizes 32A through 36E), $54; bloomingdales.com. To buy: Yummie by Heather Thompson Peyton Strapless Wire-Free Bra (available in sizes XS though L, in two colors), $42; barenecessities.com.