CORPO
Buildin' it his way, one piece at a time...
That looks like a good shape to hammer form. I would anneal the aluminum first. You can anneal aluminum by using an acetylene (no oxygen) flame to cover it in soot. Then heat the aluminum until the soot burns off.
Problem is I would have to have a torch... Not all of us have fancy tools like torches and forklifts
So I'm going to go with brute force... And a hammer!