Hi @Super secret user, thanks for your post! I recommend using the “progress half donut” shape from the Dynamic Shapes shape library. 

While these are intended to represent data or progress (e.g. 70% of completion), this is the best out-of-the-box arc shape and you can simply set the value to 100% of the maximum in order to “completely fill in the progress” and style it accordingly.

Alternatively, if you prefer to create a shape of your own, I recommend the “Flex Polygon” shape from the default Standard shape library (with rounded vertices via the Shape Options menu). 

I hope this helps! Let me know if you have additional questions.

Thanks