I would suggest picking up a small, cheap arm first. There are a few you can control via Arduino. Look at one with an MG958 15kg metal gear servo you can alread

I would suggest picking up a small, cheap arm first. There are a few you can control via Arduino. Look at one with an MG958 15kg metal gear servo you can already pick up some small objects. One you go to a large, heavy arm you need more powerful and precise motors, and the cost of mistakes dramatically increases (monetarily and physical damage).