I printed enclosures to house the power-supply and SSR and to mount the Duet. I created separate enclosures to keep the line voltage isolated.
All connections are made using aviation connectors. If doing so, make sure that your connectors are rated to high enough amperage for what you will be drawing. Some of the connectors are only rated to 2amp.
There are sufficient connector knock-outs on the duet enclosure to wire the endstops, a z probe, 7 motors (x, y, 3 z, 2 extruder), 2 hotends, 2 thermistors and 3 fans (in addition to the part cooling fan).
To connect the two enclosures, I used a 4 pin aviation connector with 2 pins being the 24V supply for the Duet and the second pair being the heated bed control signal for the SSR.
Each enclosure has 2 M5 holes available to mount it to the side of the bottom extrusions.
The power enclosure can be grounded to the frame using one of the M5 mounting bolts.
The case fan is a 5V Noctua 120mm fan that I have connected to the "fan 2" port with the jumper set to 5V instead of Vsupply.
Source code is available: