Is it forbidden to design clothes for married women to wear only in front of their husbands? And does the designer bear sin if these designs are worn in public?

A Muslim is not permitted to design immodest clothing and garments for women if it is in an environment where immodesty is prevalent among women, as this constitutes cooperation in sin and transgression. However, if the designer knows or believes that the woman will not use it for unlawful purposes, then there is no sin upon him. If the woman then acts contrary to what was known or believed of her, the sin is upon her alone.