I've done some spinning, perhaps a couple hundred parts.
If you are going to give it a try, do get the first set of dvd's from Terry Tynan.
The best grade of Aluminum for learning is 1100-0, at .040 inch thickness. A second best choice that will probably be more available, is 3003-0, at the same thickness. I could not source 1100-0 locally in less than a full coil quantity. Terry Tynan sells 1100-0 in precut blanks at reasonable prices. The -0 at the end of the alloy number is the hardness, or temper in the material. Spinning the -H14 grades of the above alloys can be done, but I would not recommend it for learning. When starting out, if the material thickness is much thinner than the .040 thickness, you will have trouble with cracking or tearing when the part is about 2/3 spun, and with the edge of the blank getting buckles. If the material is a bit thicker, it will require more force, but not be as prone to cracking and buckling.
Stay away from 6061 in any temper condition, as it work hardens rapidly, and requires annealing during the course of spinning.
Copper is somewhat expensive to learn on, work hardens, and requires annealing. Roofing copper is commonly available in 16 oz (.021in) and 20 oz (.027in). The 20 oz is on the thin side to learn on, especially with blank sizes much larger than about 6 inches.
Brass is more difficult than copper, as it work hardens faster, and is a stronger material.
----------------
Donny,
Checked out your website, and notice that you mention the cup is still thinning out and not quite thick enough to bead. You have probably gone past that problem, but if not, try using more effort on the back stroke. This will lay the metal down on the form, and help maintain blank thickness. Do you use a backstick?
--------------
A part made for the wife's xmas present a few years ago. 11" dia x 5" deep, x .027"copper. Great for egg whites.
Later,
Dale M