As far as we know, Nintendo isn't working on a 3DS version of classic Zelda title Majora's Mask. So as far as we know, they're not working on a special Majora's Mask edition of the Nintendo 3DS, either. Pity.
Fan Cameron Smith is, though, and has drawn up his idea for what such a handheld could look like, turning a 3DS XL a very purple shade of purple (it looks a little richer than the existing Midnight Purple 3DS) and adorning the front with some Majora's Mask imagery.
Not sure which I'd like more. The 3DS or the game. Presumably I'd get both in the one box if this wasn't a fantasy project, so that takes care of that dilemma.