So it turns out yesterday's custom theme tool is significant in more ways than one. Beyond editing themes, it proves that Ninjhax actually allows modification of arbitrary 3ds extdata. The most basic application of which is this, a play coin generator! Download: https://dl.dropboxusercontent.com/u/183608682/playcoin.zip Github: https://github.com/MrCheeze/playcoin This is only the beginning, I'd be very interested in seeing what could result from editing an actual game's extdata. Note that this is not the same thing as save data - extra data normally contains content that can be downloaded from the internet, such as the new Streetpass Mii Plaza puzzles. EDIT: Actually, turns out only "ARCH_EXTDATA" and "ARCH_SHARED_EXTDATA" is possible to access via Ninjhax, not "ARCH_BOSS_EXTDATA". Most spotpass data goes in the latter, and is therefore not accessible.