Check out this thread. Aluminum cutting questions - #2 by JoeN
My reccomendation is drillman1 on ebay. The local store for drillman1 is Sparktech.
Your thickness could be cut probably in 1 pass with an al cutting endmill at probably 50 ipm? I don’t know your design. I’m guessing you should use blue tape/super glue/activator as your hold down. youtube