There is already an excellent Arduino-based solution for adding a CNC pendant to a Duet control board here: https://duet3d.dozuki.com/Wiki/CNC_Pendant
However, I wanted a little more control such as the ability to run macros, set work 0 etc.
With RepRap Firmware V3.2 they added support for 12864 displays on DuetWifi (this has been in Duet Maestro for some time already) and this prompted me to come up with this solution.

The CNC pendant has enough cores in its wire to support both this display and the control signals for the Arduino.

You will need:

Arduino Micro
CNC pendant - https://www.aliexpress.com/item/1005001959925033.html?spm=a2g0o.productlist.0.0.5287ed89LQxcPz&algo_pvid=7cf436db-9d6a-4f95-9748-55fa4c31e9dd&algo_expid=7cf436db-9d6a-4f95-9748-55fa4c31e9dd-0&btsid=0b0a119a16171909949764917eb7dc&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_
4 x M3 x 20mm screws
Fysetc Mini12864 display - https://www.aliexpress.com/item/32972382466.html?spm=a2g0o.productlist.0.0.67ac7895MDf8hz&algo_pvid=24a935b6-5fe3-4d4d-80c3-6bf40fd31211&algo_expid=24a935b6-5fe3-4d4d-80c3-6bf40fd31211-8&btsid=0b0a0ac216171910497075580e7ce9&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

Note: The DuetWifi cannot control the RGB LED in the RGB version of the display but Duet3 can. I modified DC42's sketch to add a simple WS2812 control routine in there to sort mine out but you would probably be better off buying one of the single colour displays and just wiring the LED pin to VCC.

I have added a STEP file for you to modify for your own purposes. Just remember to credit me when you remix.