I know and as far as I remember this is done using a small brush to trace the outline and then fill it. Apart from being kind of a hack you also lose the beauty

I know and as far as I remember this is done using a small brush to trace the outline and then fill it. Apart from being kind of a hack you also lose the beauty and simplicity of using Metafont to describe the spine of the character and let it derive the outline from that. I always thought of that as the higher abstraction that is preferable to use, but unfortunately and unexpectedly it falls short on many common character shapes. As a bezier outline description tool I see little benefit in using Metafont.