The factory is a bit complicated pattern, but I introduce it already in Lesson 8 simply because it looks so good. I included many intermediate steps to compensate for the difficulty. If you rehearse each one until you are confident, I am sure you will get to the end. I think the learning efforts are well spent here.
Step 1 Fake columns as mentioned in Lesson 4.
Step 2 Horizontal carrying.
Step 3 Combine the previous two. Make a small stop at the turning point. Synchronize the swoops to the throws.
Step 4 Here is a two ball version of the final pattern. First throw the lower ball, then drop the higher ball. Catch the first ball high and the second ball low.
Step 5 After carrying, stop to concentrate on the rest of the pattern. Then make the break shorter.
Step 6 You are done. This favourite pattern is known with many names: the factory, robot, assembly line, or machine.
Variant After learning both sides separately, you can mix them easily. (A note on the siteswap notation: While the basic factory has an asynchronous siteswap 423342, there is a sort of a synchronous point where to switch.)