I love aluminum cases:
I had a Proporta aluminum case for my iPAQ 1910, and it was great. I loved being able to toss my 1910 in a pocket, bag, or whatever, and not worry about getting all scratched and dinged up. And the 1910 was tiny enough that iPAQ+case wasn’t too bulky.
Perhaps they’ll come out with a version for the similarly sized rx3700 series, with a camera cutout? (hint, hint!)