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[Epoxy_Rainbow]

Just like how you can lock trapdoors you should be able to lock barrels and other blocks like looms which are commonly used in building.
how it would work is the same as the trapdoor, you can sneak right click to lock then you cant open up the gui

 

[shharpp]

i like this

 

[Matanlo]

I agree, but only if the container is empty