Designing Echo as Double Weave for 16 Shafts
An aside: With double weave, the shafts that are "raised" to weave the bottom layer are actually being lowered from the perspective of the bottom layer, because the bottom layer is weaving upside down (from the weaver's perspective). It's helpful to think of the tieup for the bottom layer as a sort of photo negative, where up is down (black is white) and down is up (white is black).
Note that the second half of the tieup for both layers is totally blank. That's where Stubenitsky's ratio comes in. For this, I tried a tieup with a ratio of 4:4, meaning that, in the second half of the treadling above the ground tieup, 4 shafts are raised and 4 shafts are down in an ascending order for both layers (top and bottom layers, on odd and even-numbered treadles).
Here's how that 4:4 ratio looks.