Does anyone use op-amps for modelling physical systems any more?
Don't forget hydraulic, pneumatic and even rolling marbles!

But seriously, I saw a great model of an aquifer made with a mesh of resistors and capacitors. You could just clip the scope to any junction to get a prediction of the water level for the next century.

These days we can solve a few thousand simultaneous equations in a few seconds or less, so this aquifer model is quite redundant.

On the other hand, we use physical models all the time in very simple circuits like low pass filters, integrators. But these are for circuit convenience, never for the investigation of a physical system. So for modelling, it's easier to just do it digitally.