I've heard it said that you can take all those annoying soap slivers in your bathroom and form them into a new bar. Why? All you have to do is press the old sliver on the new bar. If they're both moist, it works like a charm. And it spares you the trouble of boiling and forming and... You get the picture. Jeez.
Simple is best, it's time tested and proven. I don't end up with slivers... but lumps. But I get the idea