Trading / Filter Block

Multiplayer worlds typically setup a market where items can be bought and sold. Often currency is diamonds, but other options are sometimes used, honor system to pay and take items, but in worlds with many players that can break down. Alternative currency is also problematic as it is hard to prevent copying.

It would be helpful to have a "Trading and Filter" block. Resources for crafting should be relatively easy to obtain (ie, no rare treasure / end items, etc).

After crafting, the block GUI would have two item slots. The player would put a set of the items being "sold" in one slot and the set of "money" items in the other slot and then "lock" the block. Once locked, the block would function as follows:

Sale items would come in from the back via hopper or dropper if the sale slot is empty (so merchandise is hidden from view). Money items can be placed by the player (purchaser) or pulled in from above (when used as a filter). Purchaser can then take sale items from the block to complete the purchase. Money items could then be pulled out of the block from below via hopper (thus also being hidden from view), and the process would repeat. In "filter" mode, Sale items would be "dropped" out the front for collection by another container.

Pointing at the block could display what is for sale and the cost automatically, or whether it is "out of stock". Items could be reset via grindstone.

- Automated filtering of non-stackable items

- Controlled trades of any two items in any quantity