Here's how I did it. I go down on Earth, then farm the steppes. I go to moth yards and farm. I then go to Skywatch and farm. After that I got back to moth yards, then steppes, and so on. If there is no spinmetal, simply go to orbit and the Spinmetal will be back. Some tips for farming are Have a ghost that marks Spinmetal Try to remember which spinmetal you took as your ghost marks it even if you take it Have a sniper. If you aim down sights with a sniper, it marks where Spinmetal is. Last but not least, be very patient.