Would it be possible to create a software tool that modifies the original model

Would it be possible to create a software tool that modifies the original model file in such a way that once the printed object is put into something like an acetone vapor bath (for ABS), that the resulting printed and smoothed model would more closely match the original design?

So the tool would essentially over-exaggerate details so that the smoothing would bring the details back towards the target.

Does not sound crazy imo, you could detect edges and details and make them more pronounced by basicaly steepening the angles between polygons, in effect the opposite to a bevel.

scale it up just a bit in slic3r, then vape away?

The problem with just scaling the model is that if parts are to be precision fit then you need holes and connectors in the right place.

Is vapor smoothing analogous to surface subdivision, like in Blender for instance?

I think it would be better as a setting in the slicing software, as the time it takes to smooth will be somewhat dependent on your layer heights.

Scaling it up doesn’t help because the vapor melts the plastic filling in the gaps. So you would have to "sharpen"the details so that at the end they would have softened into the correct shape. Imagine only rounded corners. Bjorn is definitely on the right track. You could almost do a 2-part 3dprint acetone bath with a cnc finishing cut for cleaning.

@Brian_Bartlow Yes, it is a bit like SDS, but since there is no base mesh it works on but a continous surface. What would be needed is a kind of creasing algorithm that works similar to Ambient Occlusion.
@David_Christal Scaling is no solution since it will change the over all shape and measurements, something you want to minimze.