I use AnyBar as a build monitor to display the status of our builds on the menu bar, but was thinking of doing the same on the TouchBar using BetterTouchTool. I know I can run shell scripts and display text, but:
How can I display coloured dots on the TouchBar?
(Green for successful build, red for failure, blue while building)
Here’s one example. I created a BTT Touch Bar widget and then gave it a name of a symbol.
It has a shell script that generates a random RGB colour every time the widget runs (every 5 seconds here), just for example purposes. That colour is used for the font colour in some special BTT JSON the script outputs.
cr=$(python -S -c "import random; print random.randrange(0,255)")
cg=$(python -S -c "import random; print random.randrange(0,255)")
cb=$(python -S -c "import random; print random.randrange(0,255)")
echo "{\"text\":\"â—Ź\", \"font_color\": \"$cr,$cg,$cb,255\"}"
Note, the JSON definition is covered below the result window on a widget:
In the script you can either return a simple string which will then be shown on the widget, or you can return a JSON string like this (must be escaped):
"{\"text\":\"newTitle\",
\"icon_data\": \"base64_icon_data\",
\"icon_path":\"path_to_new_icon\",
\"background_color\": \"255,85,100,255\",
\"font_color\": \"100,200,100,255\",
\"font_size\": 10}"
I’ve also set the widget background colour to black, so I just have a randomly changing coloured dot in my Touch Bar - very festive 
Anyway that’s one way of doing it if you have lots of colours.
You could also look at the alternative icon and alternate colour regex for another approach, or you could use different custom icons in the JSON above to use different icons and colours to represent different states.
Hope that helps.
That’s simple/nice! 
Unfortunately I seem to be doing something wrong (despite your clear instructions).
I use this script:
echo "{\"text\":\"●\", \"font_color\": \”255,0,0,255\"}"
I expect a red dot, but instead I get this text on the TouchBar:
{\"text\":\"●\", \"font_color\": \”255,0,0,255\"}
But this does work…
cr=255
cg=0
cb=0
echo "{\"text\":\"â—Ź\", \"font_color\": \"$cr,$cg,$cb,255\"}"
I always copy and paste the script into BTT. If I don’t, and edit in the app, I often get the a part of the script displaying instead. I think the script editor field is a bit flakey, so if you get chance, see if copy and pasting in works any better for you too.