diff --git a/Assets/Scripts/Components/PictureFrameBuilder.cs b/Assets/Scripts/Components/PictureFrameBuilder.cs
index 13059a7..62fc400 100644
--- a/Assets/Scripts/Components/PictureFrameBuilder.cs
+++ b/Assets/Scripts/Components/PictureFrameBuilder.cs
@@ -13,6 +13,10 @@ namespace Chameleon.Components
     // The generated mesh is a per-instance HideFlags.DontSave object (never saved into the scene file);
     // it is rebuilt on scene load / domain reload via OnEnable. Duplicated frames get their own mesh
     // (identified by instance id), so two frames never write into one shared mesh.
+    //
+    // GenerateColliders maintains matching BoxColliders (corner radius ignored): 4 border bars, a slab
+    // behind the inner floor, plus a plinth box when the picture is raised. Only colliders tracked in
+    // _colliders are touched - manually added ones are left alone.
     [ExecuteAlways]
     [RequireComponent(typeof(MeshFilter), typeof(MeshRenderer))]
     public sealed class PictureFrameBuilder : MonoBehaviour
@@ -52,6 +56,12 @@ namespace Chameleon.Components
         [SerializeField] Material _frameMaterial;
         [SerializeField] Material _backMaterial;
 
+        [Header("Colliders")]
+        [Tooltip("Automatically maintain BoxColliders matching the frame (corner radius is ignored).")]
+        [SerializeField] bool _generateColliders = true;
+        // Ownership list so rebuilds never touch colliders the user added by hand.
+        [SerializeField, HideInInspector] List<BoxCollider> _colliders = new List<BoxCollider>();
+
         readonly List<Vector3> _verts = new List<Vector3>();
         readonly List<Vector3> _normals = new List<Vector3>();
         readonly List<Vector2> _uvs = new List<Vector2>();
@@ -62,23 +72,31 @@ namespace Chameleon.Components
 
         Mesh _mesh;
         bool _rebuildQueued;
+        bool _rebuilding;
 
         void OnEnable() => Rebuild();
 
+        // Mesh/renderer writes are not allowed during OnValidate, so it only flags; the actual
+        // rebuild runs in Update (ExecuteAlways covers edit mode).
         void OnValidate()
         {
-#if UNITY_EDITOR
-            // Mesh/renderer writes are not allowed during OnValidate; defer one editor tick.
-            if (_rebuildQueued) return;
             _rebuildQueued = true;
-            UnityEditor.EditorApplication.delayCall += () =>
-            {
-                _rebuildQueued = false;
-                if (this && isActiveAndEnabled) Rebuild();
-            };
+#if UNITY_EDITOR
+            // In edit mode Update only ticks when the editor decides to pump the player loop;
+            // request one so the last inspector change never stays un-applied.
+            UnityEditor.EditorApplication.QueuePlayerLoopUpdate();
 #endif
         }
 
+        void Update()
+        {
+            if (!_rebuildQueued || _rebuilding) return;
+            _rebuildQueued = false;
+            _rebuilding = true;
+            try { Rebuild(); }
+            finally { _rebuilding = false; }
+        }
+
         void OnDestroy()
         {
             if (!_mesh) return;
@@ -150,6 +168,49 @@ namespace Chameleon.Components
             _mesh.RecalculateTangents();
 
             ApplyMaterials();
+            RebuildColliders(w, h, t, d, ow, oh, pw, ph, id, pz);
+        }
+
+        // Box approximation, corner radius intentionally ignored: 4 border bars (full depth), one slab
+        // filling the opening from the inner floor to the back, and a plinth box only when the picture
+        // is raised out of the floor. A sunken picture recess is NOT carved out - the slab stays full
+        // (colliders would need a per-side split for a cosmetic dent).
+        void RebuildColliders(float w, float h, float t, float d, float ow, float oh, float pw, float ph, float id, float pz)
+        {
+            _colliders.RemoveAll(c => !c);
+            int count = 0;
+            if (_generateColliders)
+            {
+                SetBox(count++, new Vector3(0f, (h - t) * 0.5f, d * 0.5f), new Vector3(w, t, d));
+                SetBox(count++, new Vector3(0f, -(h - t) * 0.5f, d * 0.5f), new Vector3(w, t, d));
+                SetBox(count++, new Vector3((w - t) * 0.5f, 0f, d * 0.5f), new Vector3(t, oh, d));
+                SetBox(count++, new Vector3(-(w - t) * 0.5f, 0f, d * 0.5f), new Vector3(t, oh, d));
+
+                // Keep a minimal slab even when the inner floor sits on the back plate, so the opening
+                // is never backless.
+                float slabFront = Mathf.Min(id, d - 0.002f);
+                SetBox(count++, new Vector3(0f, 0f, (slabFront + d) * 0.5f), new Vector3(ow, oh, d - slabFront));
+
+                if (pz < id - 1e-4f)
+                    SetBox(count++, new Vector3(0f, 0f, (pz + id) * 0.5f), new Vector3(pw, ph, id - pz));
+            }
+
+            for (int i = _colliders.Count - 1; i >= count; i--)
+            {
+                var extra = _colliders[i];
+                _colliders.RemoveAt(i);
+                if (!extra) continue;
+                if (Application.isPlaying) Destroy(extra);
+                else DestroyImmediate(extra);
+            }
+        }
+
+        void SetBox(int index, Vector3 center, Vector3 size)
+        {
+            while (_colliders.Count <= index) _colliders.Add(gameObject.AddComponent<BoxCollider>());
+            var box = _colliders[index];
+            if (box.center != center) box.center = center;
+            if (box.size != size) box.size = size;
         }
 
         void EnsureMesh(MeshFilter filter)