I'm getting into some small scale electroplating. The place I purchase my supplies from suggest a constant current, constant voltage, adjustable voltage and current power supply. These things are expensive, I could get away with a 25 amp for everything except for hard chrome, roughly it takes one amp for every square inch of surface area you want to plate.

Hard chrome is almost triple this, I would need a 200 or 300 amp power supply to attempt hard chrome, I cannot afford that.

How can current be limited? In other words, say I have 100 amps of 12 volt battery power available and I want to only allow 25 amps to flow through my cathode and anode, any idea how I would do this?

I was thinking about regulating the voltage using resistors, let's say I need 18 volts and I have two 12 volt batteries wired in series and I need 100 amps, are resisters available that will handle that amount of current? If so, are they very expensive?