The growth of the leather industry continues to increase, making the leather one of the commodities supporting Indonesia's economy. Surely this growth also affects the waste resulting from the remainder of the production of leather products. The size and color of the irregular leather waste become a barrier for the sellers and craftsmen. Sellers do not necessarily get buyers because they are sold in the form of residual pieces and craftsmen who can not get the same results in their crafts. This makes the leather waste has not treated optimally. . From this problem, there is an opportunity that can overcome the leather waste to produce a distinctive product. The effort is made to extend its life cycle by being a fashion bag using interlock technique. The design process is done using several methods, namely observation, interviews, and exploration. Fashion bag product design adapted to the lifestyle of middle to upper-class women who have a love for the environment, especially thinking about the concept of sustainability. The interlock technique is expected to cope with varying leather waste to extend its lifespan in the form of fashion bags.