This is an excellent starter project for the metal lathe; it requires several different operations, requires a minimal set of tooling, it can be done in lightweight 'free machining" aluminium, and aside from a couple of key places accuracy to within a thousandth of an inch is not required.
1" Aluminium round bar (2011 T3 is a good choice for this)
3/8" Aluminium round bar
1/4" Brass round bar (I used C360 free machining brass)
You only need a foot or two of each of these (get enough for errors!) I bought mine at OnlineMetals.com
, which I have found cheap and fast to order from. Since you are turning all of this stock down anyways, you can make do with anything that is of at least the above dimensions.
5/16" x 1" compression spring. (I used a Servalite #135U bought at Orchard Supply Hardware.)
Right-hand turning tool, medium straight knurl, parting tool -- I'll discuss the tooling more within the Instructable.
Oh, yes; and a lathe.