Spray paint should be a pretty good way to paint it. A lot of pro shops will use spray guns to paint parts, which is just the more cost effective version of spray paint. I’ve painted a few of my cabinets I made Rustoleum flat black and it looks nice 
If you don’t mind me asking, what feedrates, spindle rpm, and depth of cut do you use for aluminum? I recently experimented with aluminum cutting on the Maslow and broke a fair amount of 1/8" bits before switching to 1/4". The 1/4" bit worked, but if there is a better way to cut aluminum I am all ears.