I would modify your illustration because there are to many thin areas what will have a chance of becoming bent inward, and might flap in the wind depending on how thick you're going. If you go with aluminum, it'll have to be really thick, don't bother with steel as it will rust quickly.
I was able to find a local shop that waterjet mine for me for around $100 (but I got lucky because other places quoted me $300 and up), I paid for my own s/s sheet ($95+), and sent them my own illustration which I created in Adobe illustrator that he was able to work from since it was a vector file. I had the s/s polished to a mirror finish.