The goals of Explorer 3D would at least cover the goals of Windows Explorer: auto arrange files, drag and drop items, rename files, right click files for special context options, etc. The biggest difference would be in the visual appeal. Here's some quick concept art roughly depicting what Explorer 3D would look like (there are duplicate icons here just to show what it would look like when there are more items to display):
In the image above, there are 27 items being displayed, and 25 of them are visible because the middle item covers up two items behind it. An explorer window of the same size is capable of showing 16 items when in "list" mode, so this would actually provide a slight improvement in regards to the number of items the user can see at once.
This would be no small task, and I'm not sure how far I would be able to carry this project to completion, but you don't know what you're capable of until you try! Also, I don't really want to work on this if it's merely an eye candy performance that provides less functionality than the actual Windows Explorer.