What if the iPhone 3G's had been made from metal rather than plastic? What would the impact really have been on the performance of its antennas? Core Cases' new Aluminum Slider Case for iPhone 3G ($30) provides a pretty close answer to that question: it unashamedly covers the device in a thin layer of padded anodized black or silver aluminum, with only the barest of cut-outs for the device's ports. Our initial findings suggest a half to a bar of signal…
