MiniPC.de – Small, flexible, powerful

[upd] — Dupe+mod+1192+link

: This method requires a single chest. Place your items in a chest, save and quit, then re-enter the world. Place the items back in the chest, then immediately force-close Minecraft using Task Manager (ending the OpenJDK Platform binary). If timed correctly, the items will appear in both your inventory and the chest.

: A utility mod often used for duplication on servers by manipulating graphical user interfaces. dupe+mod+1192+link