I am familiar with soldiering wires but don't have experience soldiering brass, I suppose I don't know how hard it would be until I get into it. I might want to give that a shot. Additionally adding electronics to a scratch built 3-rail locomotive adds another layer of complexity.
Brass parts are all new to me, so I am trying to find a way of getting my feet wet without biting off too much. What common sources are there for brass parts?