The Vending Block allows players to easily accept item trades.
To set up a Vending Block, place it on the ground and right-click to open a menu. The player that placed it is the only player that can open the configuration/inventory.
The blue slot on the left is the stack accepted for trade, and the orange slot on the right is the stack that will be returned to the customer. These slots don't consume items, but can be clicked with a stack to set them.
In the center is the inventory of the block, which should contain the stock of items to distribute. Items paid by users will also appear here, so make sure to leave space for them.
Once configured, players can exchange items by right-clicking on the block with the required item in hand.
A variant of the Vending Block, this item is not craftable and meant to be used by server admins. It has no inventory, and will infinitely allow the configured trade.
A variant of the Vending Block that can interact with item transport (e.g. hoppers). Note that this weakens the security of the block, as other players could extract items.
