Distributing power to varying resistance
What you're after is a constant-current source, where the current is set, and the voltage varies according to load resistance.

This paper describes a good overview of the entire electroplating process, including a blurb about current density and plating thickness. "The current divided by the apparent area yields an average figure. Except for the simplest geometries of a cell, such as when the anode and cathode are concentric, the current is not uniform over the surface of an electrode." So if you were hoping for a "magic current value" to make everything plate wonderfully, then it doesn't exist. What will help, is placing more anodes in or near the hard-to-plate areas, such as inside circles or tubes, depressions, cavities, etc.

Surprisingly, there is little info to be found about power supplies specifically for electroplating. There are a few big vendors, such as Caswell or Mastech, and these may be fine for a commercial or industrial application. Some specialty supplies may be a "pulse" type, which either pulses the current on-of-on, or reverse the current altogether for a short time. There is some debate as to whether this may improve the resulting plate, and like everything else in electroplating, depends on many factors.