I didn't know about the memory card issues after being trimmed, I'll probs just drop that idea but for the case issue I was worried about that too but a few members said it should be fine and suggested I line it kapton tape. I'd be interested to talk to anyone who has done an aluminum case before, as someone did link a finished portable
I did a N64 portable out of aluminum a few years ago, youtube search for aluminum n64 you'll find the video of it and most of the photos in a slide show if you have enough patience to make it to the end. This was back in the day of the bacteria forum so all the commentary on it is long gone most likely.
Milling an aluminum case is pretty straight forward, plan ahead for all your mount points, holes, etc. I made all my buttons on a lathe, and was over all happy with what I made, if I had more time and money, at the time, I would have bought a more capable machine or a CNC to do it, but that was the best I could do with the anemic machine I had access too.
With anodizing, get a few samples first, I did mine in clear anodize or "natural" for the case and black for the buttons. The finish was nice, but it was beyond beyond beyond dead flat with no shine or reflectivity whatsoever, if you want a shine to it like most anodized crap out there or like the stuff Apple makes you need to get it bright dipped anodized.
Anodize will take the electrical conductivity out of it, but don't forget the anodized layer is quite thin, with enough force you can get it to short. Don't waste tape lining it, just mount your boards well and don't have any bare wires floating around in there and you'll be fine