Summary

This is an enclusore for the Duet controller board, to be mounted on the rear of the printer atop the power PCB (which also goes into the same enclosure). This is similar to where it is mounted on the Ormerod 2. Parametric design where most dimensions on the enclosure are easily customisable.
Based on existing work by bobtidey and dc42, see sources for links.

Instructions

Many features of the enclosure can be turned on or off by boolean variables in the top section. Enc_basic_inner_height can be adjusted depending on the height of your connectors, and can also be a lot lower if you don't have the acrylic lid on. enclosure_spacing controls how high the Duet is, depending on how high your bed is mounted. If it is too low, the lower mounting screws might hit the bed.
There is also an extra hole in the top for a reset button, since the one on the board is quite hard to get to. This can be wired to the reset and ground pins of the expansion header (pins 2 and 4, the two pins at the end of the row closest to the edge of the board).

To connect the power PCB to the Duet, I used 2.5mm2 solid-core electric installation cable, which is easily bent into the proper shape and works well with the screw terminals.
Some of the cables will also be too short after this. I used the loom for the Y motor and connected to the Z motor, and cut the old Z loom apart and extended it to use for Y. Similarly also had to extend the endstop cables.
The enclosure is mounted with the same screws, nuts and plywood washers as the original enclosures. The difference is the upper mount where I replaced the screw with a shorter one and no washers. The original one works but you will need one or maybe even two washers.
Before printing, verify that the Z carriage can move freely and that the Z runner does not hit the enclosure.

Some additional info can be found in the reprap forums

Rear-mounted Duet enclosure for RepRapPro Ormerod 1