Free tools for minimizing tree 3D models include Blender (Decimate modifier), MeshLab (simplification filters), and 3D Coat (free basic version).
Blender’s Decimate cuts polygon count while keeping a tree’s natural shape—perfect for quick edits. MeshLab uses algorithms like quadric edge collapse to simplify meshes efficiently without losing key details. 3D Coat’s free tier handles basic tree mesh slimming for casual users.
For beginners, start with Blender’s Decimate (Properties > Modifiers)—it’s user-friendly and fits most tree model workflows.