Controls how the top and bottom solid layers (shells) are generated.

This is the number of solid shell layers, including the surface layer.
When the thickness calculated from this value is less than shell thickness, the shell layers will be increased.

These layers are printed over the sparse infill, so increasing shell layers will increase overall part strength and top surface quality. It's usually recommended to have at least 3 shell layers for most prints.

The number of solid layers is increased during slicing if the thickness calculated from shell layers is thinner than this value. This avoids having too thin a shell when layer height is small.
0 means this setting is disabled and shell thickness is determined entirely by shell layers.

This setting controls the density of the top and bottom surfaces. A value of 100% means a solid surface, while lower values create a sparse surface.
This can be used for aesthetic purposes, improving grip or creating interfaces.

The top solid infill area is slightly enlarged to overlap with walls for better bonding and to minimize pinholes where the infill meets the walls.
A value of 25-30% is a good starting point. The percentage value is relative to the line width of the sparse infill.

This setting controls the pattern of the surfaces.
If Shell Layers is greater than 1, the surface pattern will be applied to the outermost shell layer only and the rest will use Internal Solid Infill Pattern.

The surface patterns are:

• Concentric
• Rectilinear
• Monotonic
• Monotonic Line Usually Recommended for Top.
• Aligned Rectilinear
• Hilbert Curve
• Archimedean Chords
• Octagram Spiral