How to config kikit drilled only need f.mask and b.mask on mousebit?

[retiredfeline]

Just make sure to tick the box Filled shape. The mask layer is a subtractive layer, which means where you define a filled area, mask will be removed.

This is the standard FAQ for tonnes of detail about this:

How does solder mask layer work?

What is soldermask and how does these layers work in KiCad? Solder mask is physical substance applied to the physical board. There are holes in this mask which expose copper pads. [image] Illustration: pads and solder mask openings. In KiCad (and other EDA) the graphical layer which represents solder mask is negative. Where there is graphics in this layer, the physical solder mask isn’t applied and there will be a hole in the solder mask. Expansion and Minimum Web Width There are three val…