The Zone VI is not as good a design as Fred Picker's sales copy would have you believe.
The Nova washers are more effective, and had input from Ilford in their design. The reality is that once you have enough agitation to get a good wash, the claims about fixer sinking become nonsense.
In essence, the washer is not that complicated, the best dividers are effectively prismatic diffusion material, and you need an input manifold that is effectively a box with the main inlet at one end and a small hole drilled to feed water into the bottom of each 'cell' defined by the dividers. At the top, you have one internal end wall a little lower and the water overflows/ waterfalls into an outlet channel and down the drain without mixing into other cells. 'In sink' washers don't have the containment area and just overflow directly into a sink. That's about the extent of it. Most of the complexity involves making something that can withstand 70+kg of water.