Above is a transparent 3DS XL Nintendo recently showed off in a Q&A on its site. A "clear" version hasn't been slated for sale, and this model was used in the Q&A to discuss the new plastic resin Nintendo is using for the 3DS (and how difficult it is to paint said resin).
Moreover, Nintendo used the clear 3DS XL to show where it hid the FPC (flexible printed circuit), which connects to the upper screen and is hidden in the hinge.
Clear electronics are fascinating—they do not try to mask the beauty of engineering that powers the device.
In the past, Nintendo has released several clear (or nearly transparent) handhelds—for Play It Loud Game Boy, Game Boy Color, and Game Boy Advance. It's about time Nintendo saw through the same for the 3DS or 3DS XL, no?