Data clock chart

I am working with some datasets which involve weekdays on one side and 24 hours (00:00-01:00, 01:00-02:00, etc) on the other side. I'm trying to make a data clock similar to what you find in ArcGIS, but I haven't been able to recreate the effect in Excel.
The closest I've come is a donut, and while Googling I've discovered you can make at least a 2-layer "double donut". The issue I have is the pieces are still different sizes, such as what you find in a pie chart. Data clocks have fixed width wedges, and the amount in each wedge/bin is determined by color (lighter = lower number, darker = higher number).
My goal is to have 7 rings (each weekday) and 24 fixed-width wedges (each hour).