open fbi then go to extra save data in fbi go to mario maker extra data then copy one of the course files then paste it on to your sd card. on your computer put the sd card in or use ftp then open up the course and a hex editor. copy offset 0x10 to 0x17. open the course you want to inject in a hex editor then from offset 0x10 to 0x17 replace that one from the one you copied from your course and save and put the course file on your sd card . on your 3ds go on fbi then rename the course you want to inject that's on your sd card any course number here. go to extra data of mario maker on fbi then delete the course with the number the one you want to inject has copy the course file from your sd card with fbi then go into extra data and go into mario makers extra data and paste This is what you want to replace in the hex editor with yours from your own course file note: when copying the course data from sd card to extra data you must delete the course file that has the same number as the one you want to inject before pasteing you cannot overwrite it or fbi throws an error.