This could be something also useable for future brush sets. Leave the brush icon for each category and tap & drag to choose a specific custom brush.
Better than an icon for each brush flooding your display, like in zBrush.
It won’t play well when the toolbox has more than one column, which seems to be the default for most users.
My setup for example is hidden toolbar, and square pattern when displayed.
At the moment I’m working on brush preset.
I’m not sure I want to link a derived brush to its base UI wise.
The main reason is that you might forget if a certain brush is under « Brush » or « Clay », so it might be frustrating.
For now I’m simply thinking on adding new custom brushes in the same toolbox.
And ideally something a bit more intuitive for reordering tool rather than going in Interface menu.
It’s more to keep the base like it is, but save the variations in drag menu.
That would save space and keep everything logic.
As soon as custom presets are available, the interface will be cluttered with brushes. Some only with different name, due to lack of different icons, like in zBrush. Terribly cluttered, even with shortcuts not that big fun.
Tap & drag down on brush icon to see & select last five used brushes could speed up things as well.