3D plasma/water-jet cutting

Hi,

I'm interested in plasma and/or water jet cutting on curved surfaces.
The shape (mostly circles) would be controlled by the XY plane and the
torch/nozzle normal to the XY plane (sort of a saddle-cut).

Has anyone tried this?

Can I control the torch to work distance accurately enough?

Does the plasma torch need to be so close to the work that the surface
curvature will interfere with it?

Any ideas would be appreciated.

Tom