If you want to enjoy the small pleasures inherent in using things up — or, alternatively phrased, if you are a cheap bastard who wants to avoid spending any unnecessary buck — it takes some work.
Consider the humble bar of soap. You use it, and at some point it becomes a thin shard of its former self. It could still serve its cleaning and lathering purpose, but the mechanics make it difficult. You can’t really grip it in the normal way, because the pressure of your fingers would break it into even smaller pieces. If you try to palm it instead, the slippery remnants slide from your hand. And what to do about the odd-shaped hotel soaps — the ovals, and perfect squares, and little circles, all exotically scented — that you have collected during your travels? This is why most soap ends its life cycle unhappily, tossed into the trash in frustration or melting into oblivion on the shower floor.
The solution is the soap stack. Through careful engineering and soap size matching, the cheapskate constructs a multi-bar creation that maintains the bulk and heft necessary to proper soap usage. It takes patience, and some dry aging, for the soap tails to become welded together into a functional unit, leaving you with a riotously multi-hued object. But when it works, the result is an immensely satisfying accomplishment for the practitioner of household economy.
Of course, it drives Kish nuts when I do this.