How to Use Poly Build for Retopology in Blender

Blender's Poly Build tool provides a fast, native method for manual face-by-face retopology without requiring third-party add-ons. This guide explains how to prepare your scene, configure surface snapping, and use Poly Build's built-in shortcuts to efficiently generate clean quad topology over a high-resolution sculpt.

Setting Up the Scene for Retopology

  1. Import or Select the High-Poly Mesh: Ensure your base sculpt or high-density model is centered and ready in the viewport.
  2. Create the Retopology Mesh: In Object Mode, press Shift + A and add a single Plane. Scale it down, move it close to the surface of your sculpt, and enter Edit Mode (Tab).
  3. Configure Viewport Visibility:
    • Go to the Object Properties tab (orange square icon) on the retopology object.
    • Under Viewport Display, check In Front so your new topology remains visible over the high-poly mesh.
  4. Enable Surface Snapping:
    • Turn on Snapping at the top of the viewport (magnet icon or Shift + Tab).
    • Set the Snap Target to Face Project.
    • Enable Project Individual Elements to ensure every vertex adheres tightly to the surface of the underlying model.
  5. Enable Auto Merge: In the top-right tool options, check Auto Merge Vertices (and optionally Split Edges & Faces) so vertices snap and weld together when moved close to each other.

Activating the Poly Build Tool

  1. Switch to Edit Mode (Tab) on your retopology mesh.
  2. Select the Poly Build tool from the left toolbar (icon looks like a polygon with vertices).

Core Operations and Shortcuts

The Poly Build tool alters its behavior depending on whether you hover over vertices, edges, or empty space, combined with modifier keys.

1. Extruding Quads (Fast Retopology)

  • Action: Hover over an open boundary edge, hold Ctrl, and left-click to drop a new quad directly onto the surface.
  • Continuous Strips: Move along the edge loop while holding Ctrl and clicking to rapidly generate polygon strips along muscle flows and contours.

2. Moving Vertices

  • Action: Hover over any existing vertex, left-click, and drag it.
  • The vertex will slide across the surface of the high-poly mesh according to your snap settings. Dragging a vertex onto an adjacent vertex will automatically merge them if Auto Merge is enabled.

3. Extruding Single Edges

  • Action: Left-click and drag a boundary edge directly without holding Ctrl to pull out an extrusion manually.

4. Creating Triangles / Filling Gaps

  • Action: Hover over an edge until it highlights, then click and drag from the edge midpoint toward a nearby vertex to form a triangle or close a gap between two loops.

5. Deleting Geometry

  • Action: Hold Shift and left-click on any vertex or face to instantly delete it from the mesh.

Best Practices for Clean Topology

  • Establish Boundary Loops First: Start by using Ctrl + Click to outline key landmarks such as eyes, mouth, nose, and major muscle groups before filling in large flat areas.
  • Keep Quad Density Consistent: Avoid mixing extremely small faces with very large faces unless transitioning between complex and simple areas.
  • Add a Shrinkwrap Modifier: Add a Shrinkwrap modifier targeted to the high-poly mesh on your retopology object. Set the mode to Target Normal Project to keep the mesh smoothed against the sculpt throughout the process.