There is no physics based modeling. But, you can model onto another mesh. If you go to the ribbon panel, in the Freeform tab, there's a drop down just to the right of Step Build that says Draw On: Grid. Click that and select Draw On: Surface. Then pick the mesh you want to conform to. You can change the offset negative or positive depending on how far you want your mesh to touch the target. Then you can use the Conform brushes to the left to adjust your mesh to the target. So I'd start by modeling your mesh close to another mesh, then use these brushes to tweak it right up to it. You could even start the modeling on the target mesh using the Topology and other functions in this menu that are compatible with the Draw On: command. These are really handy tools, I suggest playing with them for a while to get used to them. Print out the help pages on these as there are quite a few functions that are hard to remember.
