If changing the back of your iPhone 4 to a different glass color cover was not enough, you might be interested in transforming it into metal or in this case brushed aluminum. The process is very easy and should take you no longer than a minute. These metal iPhone 4 back cover replacements have a slight bevel edges to them which actually hurt the cameras quality by applying a bit of black vignetting corners. Some people also noted that they have lost 1-2 bars of signal when using these metal backs on their iPhone 4. I only noticed this once in a while and it did not affect my WiFi signal at all.
You can find these replacement back covers all over eBay and on CNN.cn for under $20, not a bad deal at all considering the fit and finish is pretty fantastic minus the fact that you will have a bit of camera quality issues because of the beveled design. This will also be compatible with the Apple Bumper case leaving almost no clearance as the metal back sits flush with the edges of the Bumper case. So when you lay your iPhone 4 on a table, the metal back will actually touch the surface. If you have some doubts about doing this yourself, watch the video below and see how easy this actually is!