Free tools for exporting prefab 3D models include Blender, Godot Engine, and Unity’s free Personal Edition—all suit game dev or 3D design needs.
Blender (open-source) lets you save prefabs as .blend files or export to FBX/GLB; it’s beginner-friendly with lots of tutorials. Godot exports its “scene” prefabs to glTF/GLB, a universal format for compatibility. Unity’s free tier supports exporting prefabs as FBX, OBJ, or Unity Packages for game projects.
If you’re new, start with Blender—it’s fully free, versatile, and covers most prefab export tasks.