There are many ways of doing things like this.
You can either try and create the toolpath curves that a ball nose cutter would follow to machine this surface or you can try and create the surface and machine it with a straightforward horizontal or vertical pass that just follows the surface.
It looks like your example has been machined with a left to right machining operation.
It reminds me of a few examples…
Describe this force field type pattern please
Need some help to create chisel wood textures in grasshopper