Infinite Soap Bar
Used soap bars get dry and then cracks. Usually you have three options: throw away de remains, try to make a mini-soap-ball compressing the little pieces whith your bare wet hands or try to attach the remains to a new soap bar.
Problems with this options are you throw away usable soap or have to constantly keep preasure and humidity to the new mini-soap-ball to keep it together.
A solution will be a simple shape change, a dent, that will allow new ones to be filled with the remains of used ones, ad infinitum.
zero waste life cycle