My friend RaveBomb has been working on his own factory designs with a few layout and supply constraints, and posed me a challenge:  "Make a factory fed by PLS that fits into 40x80 and spits out 28.8K magnetic coils a minute, assuming proliferated inputs.  It must also proliferate the outputs.  And it must use sushi-belts!"  I was only too happy to accept!

Assembly and Usage Notes:

REQUIRES max-level ILS/PLS output stacking.
REQUIRES MK2 belts--the sushi-belts don't balance or feed properly without them.

Like all sushi-belt designs, there is a jam scenario.  In this case, it's feeding product in before all the belts are finished being laid down.  To avoid that, make sure you don't have any splitters in your inventory when assembling.  When everything else is laid down, THEN add splitters to your inventory and place them.

That said, if you avoid the initial jam scenario, you shouldn't have any problems once it's assembled, even if a component dries up or the PLSes all fill up.  Assuming it does jam, the multiplexers at the head of each assembly line make for a convenient spot to pull components off the line to un-jam it.

The sushi-belts were a fun challenge to balance; after a lot of experimenting, I went with rate-limited belts (hence the MK2s) and a combination of max-level stacking from the PLS and flipping a piler around to UN-stack the copper to achieve the proper 2-to-1 ratio of magnets and copper ingots.  I hit upon that after initially working on the assumption that I'd be feeding a line of 8 assemblers with one belt, but couldn't balance it right--doubling the number of assemblers made all the numbers line up happily and solved the de-multiplexing issues.

This little guy will take rip-roaring chunks out of your local magnet supply, hence the name!

Feel free to dissect it for parts and the like; I'm pretty happy with the multiplexers and piler layout, and this has proved instructive for the various other projects I'm working on.  (You can see one of said projects in the background, a new revision of one of my previous E-ILS smelters.)