Allows Ninjhax users to modify the 3DS's play coin counter, in other words providing infinite play coins.
Usage is self-explanatory, just choose the number of coins you want from the list, then exit using B. No more than 300 coins can be held at a time, this is a system limit. An option is also available to backup and restore the decrypted gamecoin.dat to the SD card, however this is not likely to be useful to anybody.
Note that this code is simply a modification of yellows8's 3ds_homemenu_extdatatool, which contains within it code to modify arbitrary 3ds extdata.
Precompiled download: https://www.dropbox.com/s/8ncxrv4hevssz4g/playcoin.zip?dl=0