Originally Posted by audsgirl

It makes sense to add the borders as you go along. Maybe I'll do that, too.

I was confused about the yellow QST units, too. I spent an entire day experimenting and tried all sorts of different substitutions for that unit, which gave me an understanding of its function. I believe the unit is about connecting the blocks to one another for flow (the purple 4-patch), but also creating a separation (the green and yellow), because when the blocks are entirely connected using all purple, they look very massive and you lose the circular effect. The green and yellow also liven things up amidst all of that purple.