I have almost finished my Metal nano case. Here is what I have so far. The metal is actually from a metal PC case. The bay inserts fit perfectly for the width. I just needed to cut the length to fit. You might want to try this with the plastic case inserts These are aluminum and it is very slim and light still fits perfect in my pocket. I have been debating wether or not to cut control access windows. I do have access to the headphone jack when closed Behind the iPod the metal is covered with a thin layer of suede to protect it.
Pictures
Pictures