... a house, constructed (forgive the potential violence of this metaphor) of people, animals, plants, and other materials. It has been built, it's there, and, as long as it's maintained, you can live in it. The problem is, you might not be able to arrange the furniture however you like - the way the house was built affects the way you might arrange it. Sometimes, you might neglect certain portions of the house, and those parts might fall apart gradually. You might also build new parts to the house, re-decorate, or reshape the house in other ways, but even those changes will in part be dictated by the current structure of the house. You might, if you so desired, completely demolish the house (I'm not sure how you'd do this with culture, but I'm willing to play with the metaphor). If you did, though, you'd have to sleep outside, which may not be terribly comfortable. Then later, if you wanted to get a new house, you'd have to build it up bit-by-bit over time. Houses don't simply appear out of nowhere. And there are always flaws with houses - you might have the best architect, the best models, and the best set of plans, but you'll never know what those flaws are until the house is built and you're living in it.
Another problem is that it doesn't say much about how cultures are composed. The metaphor of putting together wood, metal, fabric, and other materials doesn't really equate to humans composing associations. It doesn't explain why some associations hold together better than others or why individuals would prefer existing associations over new ones. I think, in some sense, this latter is an issues of thermodynamics. It takes less energy to simply follow established pathways than it does to blaze new trails. If a trail is left unused for a period of time it may become overgrown, but the more used a trail is, the less overgrown it is and the easier it is to travel. Hey, there's another metaphor! I like it, too, because trails are usually blazed in relation to the landscape. They wind through trees, cross over rivers, go up slopes, and interact with the landscape in a lot of complex ways. But they're not determined by the landscape. If someone wants to go straight up a cliff - the trail can go that way. If they want to avoid the cliff - then they'll find another way around (or, in some cases, blow the cliff away). This metaphor doesn't convey the heterogeneity of the composition of culture like the house/shanty town metaphor does. That's okay, though.
So Culture is like a house - or maybe a shanty town - but it's also like a trail, or a network of trails. What other metaphors for Culture are there?