All credit to Katherine of Sky, found this layout in one of my saved files from version 0.15 when I was following her playthrough, which still works great today.
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There are 2 yellow belts coming in on the outside of the assembling machines, these bring in a [FULL] belt of copper plates.
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1 red belt coming [IN] up the middle is for iron plates: [FULL] belt
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1 yellow belt for [OUTPUT] down the middle, this is lane #1 on your bus. Has a little picker for your personal stash when needed
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3 yellow belts for [OUTPUT] on the outside of the assembling machines, the balancers will even them out. Gives you options to have 1-3 additional lanes on your bus. [RECOMMEND: At least a 4-lane bus for Green Circuits]
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Good for early game; you upgrade electric poles, inserters, belts and assemblers as you wish.
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To tile this endlessly, look for "Green Circuits - Add on", uploaded by me.
Enjoy! Please favorite!