command /customitems:
trigger:
open chest inventory with 6 rows named "{@b}" to player
set slot 0 of player's current inventory to stone of unbreaking 1 named "{@a}" with lore "&a1k" with nbt "{HideFlags:61}"
I don't know how to use gui but
So, when you make a gui and click on your own inventory (slot 0 in this case) the effects will happen, idk how to fix it