Add compactor input handler second slot isItemValid check. Always return false so items can't go in. Store the value of the item placed in the slot and render it as a fake item. Set the recipe based on the item added. For automation and JEI transfer handler, set a "target" ItemStack. In fact have the input handler also do that. Button to clear the target for recipes without a target or so you can get a default recipe for things that don't have multiple outputs. The main issue is syncing between client and server which recipe is set and the ItemStack to render. Requires a packet.

Fixed in edaf72e