theres a bug that alows you to take any item that alows you to move its slot in any game, like the bow and arrow in the mob factory game.

to do this you need to:

enter the game you want the item from like mob factory or bug catcher game.

when you are about to be kicked out, take the item out of you invintory. 

when it kicks you out, enter you invintory and click the slot you want it in, it should apear in

that slot.

after all of that you should have the item you want.

notes:

any item from the mob factory will disaper when bringing it to the lobby, but the dev hammer does not.