Did this yesterday. I broke my iPhone 4s last month; the screen, chassis and backplate. It was a mess. My options were to get a new iPhone ($300 for my 32 gb), or get the parts and replace it myself ($180). I had to order new parts, so I went to iphone4parts.com and ordered a white faceplate LCD ($60), metal chassis ($100) and brushed metal backplate ($20).
It was a very complicated process- it literally took me an entire day. The worst part was the screws. They’re so small you can barely see them, and the only way to unscrew them is by using the world’s smallest screwdriver. There’s like 50 of them. Apart from that, the iPhone is built very well, and the parts are (relatively) easy to replace.
Then I turned it on…And on came a light blueish flickering screen that looked like someone nuked my iPhone in radiation poison. It works, but something is off with the color calibration. They sent me a faulty LCD screen, those bastards. I asked them to send me a replacement.
At least the custom backplate looks sweet.