I'm not aware of any parts made from just nickel. They most likely would have been small cast parts. Nickel is used in chromoly to make it stiff, it's what gives stainless steel it's corrosion resistance property and it's used in plating. Nickel by itself is fairly brittle and it doesn't form well, ever bend stainless? It's melting point is about 2700f (same range as steel) so it would be pretty difficult (and expensive) to do at home. Separating nickel from steel would be equally difficult (the nickel content is normally very small as well). If it's a nickel finish you're after nickel plating is fairly inexpensive. There are industrial platers that will do the plating for you. To get a good price you'll need to buff, wheel, polish or sand the parts. The plating is like a "clear colored" finish so the way the part looks before is the way it will look after only nickel colored. Nickel plating is very corrosion resistant so it is ideal for exterior parts. If the parts are small you can even do it yourself. Vinegar, nickel oxide, stainless rods and a battery charger is all you'll need. Search the internet and you'll find some how to's.