Based on 3DS Rom_Tool By 3DS_GUY
You need .Net Framework 4 run this app.
You can add multiple files. It supports English.
Now To use this app , you must download the 3ds rom_tool by 3DSGUY(http://gbatemp.net/threads/3ds-rom-tool-rom_tool.349314/). Rename the rom_tool to "RT.exe" and put it to the GUI's directory.(My Apologies to add the original app.)
Thanks to my friend Simon You to add dragdrop function! We're classmates.