I had just typed up a very descriptive, but short reply of my setup and when I clicked post, I got a site error message and lost it all, end rant.
In the 3 attached photos, I show the 2 boxes near one another. The outlets box is the control center as it houses an 8 channel relay, an Ethermega mounted to a piece of plexiglass that itself is mounted about 1/2 way into the depth of the box. There is also a long breadboard stuck to the plexi that has plenty of room left that I can add 4 TB6612 motor driver circuits from sparkfun. Each will turn 2 motors. The motors will only ever rotate a single direction so I'm reclaiming an otherwise used pair of pins on the mega per each circuit. I also have another long breadboard to use in the project if I decide to put the motor drivers in the pumps box and import that logic. If I use the drivers in the outlets box, I would then be sourcing out the regulated voltage (PWM).
I must also say that I am planning for very near future upgrades by also adding 4 BNC connected probes, as many as 20 actuated valves and possibly another 8 channel relay module. This project is also connected to my Android phone via Blynk and already transmits RTC and DHT22 readings. I've also been able to toggle any of my relays over the web which leads me to believe I can also control any of the sensors and devices from abroad which IMO, will make gardening damn near brainless, but if nothing else, damn near effortless. It was the desire to automate my garden that brought me to Arduino and I hope to have this project in its entirety fully up and online in 6 months.
All that said, I hope to keep the volume of wires that stem from the outlets box as minimal as possible as I know there will still be many, but simply for aesthetics sake, it would be nice to have one cable/ribbon easily connect to each box to link them together, another cable/ribbon to connect all the valve controls in and the 4 BNC connectors will terminate on the side of the outlets box.
I don't know if the motors are brushed or not, but I think they are based on the cost of each 4 head unit compared with the going rate of a single dosing head. The mast unit cost me $80 ($20 per head). An adaFruit pump is $25, fleabay roughly$15, but I presume for the price, they all use brushed.