I don't like to waste soap. When a bar of bath soap is worn down to a sliver, I like to stick it onto a new bar, so that it will be used up. This isn't always easy, though, because the old bar and the new bar both have convex surfaces, and so might not have enough surface area in contact to adhere well. It helps if the old bar is thin enough to be flexible, but then it sometimes breaks. If it's too thick to bend, it adheres for a while and then falls off.
So my idea is: every new bar of soap should come with at least one molded *concave* surface, with its curvature designed to match the curvature of a worn-down sliver of the same kind of soap. This would maximize the area of contact without having to deform the old sliver.-- Jim Bob of Merriam Park, Nov 21 2009 Nice idea, and I share your dismay at the last stuff.+-- blissmiss, Nov 21 2009 My soap swells with use. It gradually soaks up water and becomes softer until it's liquid soap. So it's not so much a problem with my stuff. Still, [+].-- nineteenthly, Nov 21 2009 The soap bars in my house (Dove I think) have a concave side with their logo. Not only does it accommodate the old sliver consistently, the logo also holds the sliver in place.-- Bad Jim, Nov 21 2009 Soap slivers can be melted in a microwave oven and re-cast into larger blocks.-- 8th of 7, Nov 21 2009 random, halfbakery