Every repair step, every parameter, and a drawing of what it actually does to your geometry. Read it once and you will know which switches to touch, which to leave alone, and why the order matters.
Open the panel, run Analyze Mesh to see what is wrong, then enable only the steps you need and press Apply Fix. Steps run in order from top to bottom, so an earlier step feeds the next one. You can save a set of settings as a preset and reuse it on similar meshes.
Cleanup steps come first (unite, fix edges, fix faces), then repair (self intersections, holes), then the heavy reshaping (voxel, remesh, reduce). Turning on a later step does not undo an earlier one, it builds on it.
Most meshes only need the top cleanup steps. The Voxel rebuild is powerful but destructive, so treat it as a last resort, not a default. If the top steps already make the mesh watertight, stop there.
After Analyze Mesh the panel lists what it found. These four numbers tell you which steps you actually need. A clean sculpt shows near zero across the board; a mesh that needs a rebuild shows tens of thousands.
Each step below shows what it does and what every exposed parameter controls, with a before and after drawing. The mesh problem is drawn in red, the result in green.
Merges vertices that sit almost on top of each other into a single point. This closes hairline cracks and welds seams that look joined but are actually two separate edges.
The maximum gap between two vertices for them to be welded into one. If two points are closer than this value, they merge. Larger values weld wider gaps but can also pull genuine detail together, so keep it small.
Limits welding to vertices on open edges (the rim of holes and seams), leaving interior vertices untouched. Use it when you want to close seams without disturbing the density of the surface inside.
Repairs edges shared by more than two faces. A clean printable surface is manifold, meaning every edge belongs to exactly two triangles. Where three or more meet, the surface has no clear inside and outside, and the slicer cannot tell solid from air.
There is nothing to set. The step finds edges with three or more attached faces and separates them into valid two face edges, so the surface becomes cleanly orientable.
Removes triangles that carry no real shape: zero area faces, needle thin slivers, and micro edges. These are the usual cause of the degenerate face count in the analysis, and they wreck booleans and slicing.
A triangle's aspect ratio is its longest side divided by its shortest. A healthy triangle is near 1. A sliver can be hundreds or thousands. Any triangle above this value is treated as degenerate and removed.
Edges shorter than this are collapsed to a point. They add weight and numerical noise without adding shape. This is what clears most of the short edge count from the analysis.
A safety cap on how far the surface is allowed to move while fixing a face. The repair will not shift geometry more than this, so real shape is preserved.
Limits how much a face normal may rotate during the fix. It protects sharp edges and flat facets from being rounded off while slivers around them are cleaned.
Decimate removes the bad triangle by collapsing it into its neighbours, keeping the surface continuous. This is the safe default. Other modes trade cleanup strength for how much they may alter the surrounding mesh.
Separates parts of the surface that pass through each other. It nudges vertices apart until the overlap is gone. It moves the surface to do this, so on a very broken mesh it can visibly change the shape. A handful of intersections relax cleanly; tens of thousands usually point to a rebuild.
Relax smooths and pushes the overlapping vertices apart in small moves. It is the gentlest way to clear intersections without rebuilding, but because it shifts vertices it also softens nearby detail.
How far out from each intersection the tool is allowed to reach when moving vertices. A low value keeps changes tight around the problem; a high value spreads the work over a wider area and deforms more of the surface.
How many smoothing passes to run. Many small passes move the surface less than a few big ones, so raising iterations while keeping Max Expand low is the gentle way to clear stubborn intersections.
Closes open boundary loops so the mesh becomes watertight. It stretches a triangle patch across each hole. This is what drives the hole count in the analysis to zero.
How finely the patch that closes a hole is subdivided. More subdivisions let a large or curved hole be filled with a patch that follows the surrounding shape instead of a flat cap.
Adds a thin ring of triangles around the filled hole to blend the new patch into the existing surface, avoiding a sharp lip at the seam.
Rebuilds the whole surface from a 3D grid of cells (voxels). It guarantees a clean watertight result from almost any input, which is why it fixes meshes nothing else can. The cost is that it resamples everything onto the grid, so fine detail is lost. Use it only when the steps above cannot clear the self intersections.
This step replaces your geometry. The detail you keep is decided here, by the grid resolution, before reduction ever runs. If you can make the mesh watertight without it, skip it.
The size of each grid cell, and the single most important setting for detail. A small cell captures fine features but produces a huge triangle count and uses far more RAM and time. A large cell is light but smooths detail away. This is the trade you are really making when a rebuild looks either bloated or soft.
With Auto Voxel Size on, you set a Target Voxel Count instead of a cell size, and the tool picks a cell size to hit that budget. Handy for consistent output across meshes of different sizes. With it off, you set the cell size directly, which is more predictable.
Resamples the whole surface with triangles of one uniform size. It replaces a messy mix of long, thin and tiny triangles with an even grid, which removes the awkward faces that cause boolean and slicing errors and gives later steps a clean base to work on.
The target length for every edge after remeshing, which sets the uniform triangle size. Shorter edges hold more detail but raise the triangle count; longer edges are lighter but coarser.
Cuts the triangle count while keeping the shape. It is curvature based: it collapses many triangles on flat areas where they add nothing, and keeps them dense on curves and edges where they carry detail. This is the step that brings weight down without visibly hurting the model, and the natural finisher after a voxel rebuild.
The largest distance the reduced surface is allowed to drift from the original. It is the one dial that sets the balance: a small value keeps more triangles and more fidelity, a larger value removes more triangles and saves more weight. Because the reduction is curvature aware, raising it thins the flats first and protects curves and edges longest.
Same detail at a lighter weight is only possible up to a point: at a fixed format, detail equals triangle count equals size. Curvature based reduction gives the best ratio there is, but it cannot beat that limit. If a mesh had to be voxel rebuilt first, its detail was already set by the grid, and no reduction setting recovers it.
Three starting points. Enable the chipped steps, leave the struck through ones off, and adjust from there.