diff --git a/src/presa_mano/clients/open3dmodel_cache.py b/src/presa_mano/clients/open3dmodel_cache.py
new file mode 100644
index 0000000..29e5113
--- /dev/null
+++ b/src/presa_mano/clients/open3dmodel_cache.py
@@ -0,0 +1,45 @@
+"""In-memory LRU cache of parsed STL meshes, keyed by recipe_id + etag."""
+from __future__ import annotations
+
+from collections import OrderedDict
+from dataclasses import dataclass
+
+import numpy as np
+
+from ..perception.stl_sampler import parse_stl_bytes
+from .open3dmodel import Open3DModelClient
+
+
+@dataclass(frozen=True)
+class RecipeMesh:
+    vertices: np.ndarray   # (M, 3) float64, mm in model frame
+    triangles: np.ndarray  # (T, 3) int32
+    etag: str
+
+
+class RecipeMeshCache:
+    """LRU keyed by recipe_id. On hit, validates the etag against the client
+    and re-fetches if it changed. Singleton-friendly: thread-safe with a
+    simple lock is NOT implemented (presa-mano is single-process; if
+    concurrency becomes a need, wrap the OrderedDict ops in a lock)."""
+
+    def __init__(self, client: Open3DModelClient, capacity: int = 8):
+        self._client = client
+        self._capacity = max(1, int(capacity))
+        self._store: OrderedDict[str, RecipeMesh] = OrderedDict()
+
+    def get(self, recipe_id: str, client: Open3DModelClient | None = None
+            ) -> RecipeMesh:
+        c = client or self._client
+        body, etag = c.get_stl_bytes(recipe_id)
+        cached = self._store.get(recipe_id)
+        if cached is not None and cached.etag == etag:
+            self._store.move_to_end(recipe_id)
+            return cached
+        verts, tris = parse_stl_bytes(body)
+        mesh = RecipeMesh(vertices=verts, triangles=tris, etag=etag)
+        self._store[recipe_id] = mesh
+        self._store.move_to_end(recipe_id)
+        while len(self._store) > self._capacity:
+            self._store.popitem(last=False)
+        return mesh
diff --git a/tests/test_recipe_mesh_cache.py b/tests/test_recipe_mesh_cache.py
new file mode 100644
index 0000000..7786eb4
--- /dev/null
+++ b/tests/test_recipe_mesh_cache.py
@@ -0,0 +1,101 @@
+"""Unit tests for RecipeMeshCache."""
+from __future__ import annotations
+
+from unittest.mock import MagicMock
+
+import numpy as np
+import pytest
+
+from presa_mano.clients.open3dmodel_cache import RecipeMesh, RecipeMeshCache
+
+
+def _verts_tris():
+    verts = np.array([[0.,0.,0.],[1.,0.,0.],[0.,1.,0.]])
+    tris  = np.array([[0,1,2]], dtype=np.int32)
+    return verts, tris
+
+
+def _mock_client(stl_bytes_by_id: dict[str, tuple[bytes, str]]):
+    """Mock client whose get_stl_bytes returns the registered (bytes, etag)
+    for each recipe_id, and counts calls."""
+    m = MagicMock()
+    m._call_count = {}
+    def _get(recipe_id: str):
+        m._call_count[recipe_id] = m._call_count.get(recipe_id, 0) + 1
+        return stl_bytes_by_id[recipe_id]
+    m.get_stl_bytes.side_effect = _get
+    return m
+
+
+def test_cache_miss_then_hit(monkeypatch):
+    verts, tris = _verts_tris()
+    monkeypatch.setattr(
+        "presa_mano.clients.open3dmodel_cache.parse_stl_bytes",
+        lambda b: (verts, tris),
+    )
+    client = _mock_client({"r1": (b"STL1", "etag-A")})
+    cache = RecipeMeshCache(client=client, capacity=4)
+
+    m1 = cache.get("r1")
+    assert isinstance(m1, RecipeMesh)
+    np.testing.assert_array_equal(m1.vertices, verts)
+    np.testing.assert_array_equal(m1.triangles, tris)
+    assert m1.etag == "etag-A"
+    assert client._call_count["r1"] == 1
+
+    # secondo accesso: la cache valida l'etag (refetch dei bytes, sempre)
+    # ma evita il parse -> identity preserved sull'oggetto RecipeMesh.
+    m2 = cache.get("r1")
+    assert m2 is m1
+    assert client._call_count["r1"] == 2
+
+
+def test_cache_etag_change_refetches(monkeypatch):
+    verts, tris = _verts_tris()
+    monkeypatch.setattr(
+        "presa_mano.clients.open3dmodel_cache.parse_stl_bytes",
+        lambda b: (verts, tris),
+    )
+    client = MagicMock()
+    seq = iter([(b"STL_OLD", "etag-A"), (b"STL_NEW", "etag-B")])
+    client.get_stl_bytes.side_effect = lambda rid: next(seq)
+    cache = RecipeMeshCache(client=client, capacity=4)
+    cache.get("r1")
+    m2 = cache.get("r1")
+    assert m2.etag == "etag-B"
+    assert client.get_stl_bytes.call_count == 2
+
+
+def test_cache_lru_evicts_oldest(monkeypatch):
+    verts, tris = _verts_tris()
+    monkeypatch.setattr(
+        "presa_mano.clients.open3dmodel_cache.parse_stl_bytes",
+        lambda b: (verts, tris),
+    )
+    client = _mock_client({
+        f"r{i}": (f"S{i}".encode(), f"e{i}") for i in range(10)
+    })
+    cache = RecipeMeshCache(client=client, capacity=3)
+    cache.get("r1"); cache.get("r2"); cache.get("r3")
+    # r1 e' il piu' vecchio
+    cache.get("r4")  # evict r1
+    cache.get("r1")  # miss -> re-fetch (call_count va a 2)
+    assert client._call_count["r1"] == 2
+
+
+def test_cache_get_uses_overrideable_client(monkeypatch):
+    """`get(recipe_id, client=other)` permette di passare un client fresco
+    (utile quando PUT /api/config cambia base_url)."""
+    verts, tris = _verts_tris()
+    monkeypatch.setattr(
+        "presa_mano.clients.open3dmodel_cache.parse_stl_bytes",
+        lambda b: (verts, tris),
+    )
+    default_client = _mock_client({"r1": (b"S1", "e1")})
+    override_client = _mock_client({"r1": (b"S2", "e2")})
+    cache = RecipeMeshCache(client=default_client, capacity=2)
+
+    m = cache.get("r1", client=override_client)
+    assert m.etag == "e2"
+    assert default_client._call_count.get("r1", 0) == 0
+    assert override_client._call_count["r1"] == 1