I started using the chord discs with students who benefitted from the physical moving of a note in a triad rather than talking about it, or writing it on paper. They proved to be a lot more useful than I imagined and I now use them in many different ways.
You will find the discs on the muscle skills sheets.
They started as simple discs laminated for ease of use. Following this I found I required them at the piano, so invest in some incredibly useful Velcro spots and to use a random A3 clipboard I use for lesson scheduling. As my current students moved up in their abilities more discs were required so an overhaul of the plan and the current format was achieved. Each disc has a colour around the edge which corresponds to the Junior program colours. The minor keys, as per tradition, are represented with a lower case letter. The font chosen in Open Dyslexic (https://opendyslexic.org/) this is because the a is a traditional 'a' as opposed to the style shown here that children do not write at school.