Scientists (or at Least Theoreticians) as Cartographers

An interesting (and seemingly eternal) philosophical debate in science is that of scientific realism versus instrumentalism. My own experience seems to indicate that quite often, it's actually scientists (and in particular physicists) who advocate an instrumentalist standpoint, while many philosophers argue a realist standpoint.

When non-scientist friends and family ask me the dreaded question "What's the aim of your work?", I'm never quite sure how to frame my answer. This is particularly true when I'm asked "Aren't scientists looking for the ultimate truth?" (no, we're looking for grant money and pizza). Lately, I've come up with a reply that I think helps me explain my aims while remaining relatively agnostic about the realist vs. instrumentalist debate:

I tell them I'm a cartographer.