Place a crate next to a series of machines, place some items in the crate, then use the activation item (Roo Poo by default) on the crate to start your Assembly Line and watch your machines go to work.

Any items in the crate that can be put in any of the machines touching the crate or, touching other machines touching the crate, will get deposited into the machines as if you had put them there yourself.  Your Assembly Line will continue to work on its own, until there is nothing left in the crate to process.

You can have multiple Assembly Lines processing at the same time, or even multiple crates feeding the same Assembly Line (each crate needs to be activated or deactivated individually).

Your Assembly Line output will drop on the ground next to each machine as if it had been deposited normally.  Don't forget to pick up your items before saving and exiting!

You will receive milestone, task, and xp credit like normal, for each item processed.

You can use the activation item on the crate again, or open the crate while it's working, to stop the automation.

You will receive a small notification off to the side whenever Assembly Line starts or stops.

Assembly Lines only work outside, on your main island.  That is, not indoors, in the Deep Mines, in the Undergrove, or on the Reef Islands.

Multiplayer:  Only works for the host, disabled for the client. However, the client can set up the crates and machines and just have the host activate the Assembly Line.

Config Options:

• Item ID used to activate Assembly Line. (Default: 272 [Roo Poo])
• Leave One: Leave at least one of each item as a placeholder. (Default: False)
  

***NOTE: There is a lot going on here, and testing every single use case is difficult. I've tried to make sure everything works well, but back up your saves just in case.