I would think for the aluminum, a hefty, sharp cold chisel & 4 lb. sledge. (and good aim)

In my opinion the Cut Off Saw at Harbor Freight (at the address below) would be most ideal for this job and others larger. The 1/8â thick X 14â dia wheel last good for accurate metal cuts. The smaller blades works good on skill saws but w/o the good base and vise for production work. A smaller saw will be best for this present job.

To be honest, a good pair of Wiss or etc tin snips should do your job w/o the dust, noise and danger.

http://www.harborfreight.com/catalogsearch/result?q=chop+saw