Realtime MatCaps Painter

Like something I want to create matcap by my own so it is stylized and applied it to some part of a mesh, is there a way for a feature for me to:

1. Paint inside a folder that can be consider as matcap material

2. Then assign this folder to the part of the mesh I want it to apply

3. Finally in the viewport to have another view call matcap view so I can paint the matcap in a circle shaped thing?

This way I can paint matcap and see it applied to a mesh in real time, I don't think there is any software that does this