diff --git a/src/dodal/beamlines/i22.py b/src/dodal/beamlines/i22.py
index a72082a90a..00c939c36f 100644
--- a/src/dodal/beamlines/i22.py
+++ b/src/dodal/beamlines/i22.py
@@ -5,6 +5,7 @@
 
 from dodal.common.beamlines.beamline_utils import (
     device_factory,
+    device_factory3,
     device_instantiation,
     get_directory_provider,
     set_directory_provider,
@@ -43,8 +44,7 @@
 
 
 @device_factory(lazy=True)
-def saxs(
-) -> PilatusDetector:
+def saxs() -> PilatusDetector:
     return NXSasPilatus(
         "-EA-PILAT-01:",
         name="saxs",
@@ -374,3 +374,12 @@ def linkam(
         wait_for_connection,
         fake_with_ophyd_sim,
     )
+
+
+@device_factory3(lazy=True, fake=True, post_create=None, timeout=10)
+def test_device():
+    return AravisDetector(
+        prefix="TEST:",
+        name="test_device",
+        directory_provider=get_directory_provider(),
+    )
diff --git a/src/dodal/common/beamlines/beamline_utils.py b/src/dodal/common/beamlines/beamline_utils.py
index dc52eb2093..a011c9ac68 100644
--- a/src/dodal/common/beamlines/beamline_utils.py
+++ b/src/dodal/common/beamlines/beamline_utils.py
@@ -1,6 +1,5 @@
 import inspect
 from functools import wraps
-from typing import Type, Callable, Optional, TypeVar
 from typing import (
     Callable,
     Dict,
@@ -9,6 +8,7 @@
     List,
     Optional,
     Protocol,
+    Type,
     TypeVar,
     cast,
 )
@@ -90,7 +90,7 @@ def __call__(
 F = Callable[[], D]
 
 _factory_made_devices: Dict[DeviceFactory, OphydV2Device] = {}
-_device_is_lazy: Dict[, bool] = {}
+_device_is_lazy: Dict[DeviceFactory, bool] = {}
 
 
 def device_factory(lazy=False, set_name=True) -> Callable[[F], DeviceFactory[D]]:
@@ -114,11 +114,11 @@ def factory(connect=False, timeout: float = DEFAULT_TIMEOUT):
     return wrapper_around_device_init
 
 
+T2 = TypeVar("T2", bound=OphydV2Device)  # Generic type for devices
 
-T = TypeVar('T', bound=OphydV2Device)  # Generic type for devices
 
-def device_factory(lazy: bool = False, fake: bool = False, wait: bool = False):
-    def decorator(func: Callable[..., T]) -> Callable[[], T]:
+def device_factory2(lazy: bool = False, fake: bool = False, wait: bool = False):
+    def decorator(func: Callable[..., T2]) -> Callable[[], T2]:
         _cache = None
 
         @wraps(func)
@@ -129,7 +129,9 @@ def wrapper() -> T:
 
             device = func()
             if fake:
-                device = make_fake_device(device)  # Assume make_fake_device modifies the device for simulation.
+                device = make_fake_device(
+                    device
+                )  # Assume make_fake_device modifies the device for simulation.
             if wait:
                 device.wait_for_connection()  # Assume wait_for_connection is a method of the device.
 
@@ -137,6 +139,7 @@ def wrapper() -> T:
             return device
 
         return wrapper
+
     return decorator
 
 
@@ -214,3 +217,61 @@ def get_directory_provider() -> UpdatingDirectoryProvider:
             "DirectoryProvider has not been set! Ophyd-async StandardDetectors will not be able to write!"
         )
     return DIRECTORY_PROVIDER
+
+
+@skip_device()
+def device_factory3(
+    name: str,
+    prefix: str,
+    not_lazy: bool,
+    fake: bool,
+    post_create: Optional[Callable[[T], None]] = None,
+    timeout: float = DEFAULT_CONNECTION_TIMEOUT,
+    bl_prefix: bool = True,
+    **kwargs,
+) -> T:
+    """Method to allow generic creation of singleton devices. Meant to be used to easily
+    define lists of devices in beamline files. Additional keyword arguments are passed
+    directly to the device constructor.
+
+    Arguments:
+        device_factory: Callable    the device class
+        name: str                   the name for ophyd
+        prefix: str                 the PV prefix for the most (usually all) components
+        wait: bool                  whether to run .wait_for_connection()
+        fake: bool                  whether to fake with ophyd.sim
+        post_create: Callable       (optional) a function to be run on the device after
+                                    creation
+        bl_prefix: bool             if true, add the beamline prefix when instantiating, if
+                                    false the complete PV prefix must be supplied.
+    Returns:
+        The instance of the device.
+    """
+    already_existing_device: AnyDevice | None = ACTIVE_DEVICES.get(name)
+    if fake:
+        device_factory = cast(Callable[..., T], make_fake_device(device_factory))
+    if already_existing_device is None:
+        device_instance = device_factory(
+            name=name,
+            prefix=(
+                f"{(BeamlinePrefix(BL).beamline_prefix)}{prefix}"
+                if bl_prefix
+                else prefix
+            ),
+            **kwargs,
+        )
+        ACTIVE_DEVICES[name] = device_instance
+        if not_lazy:
+            call_in_bluesky_event_loop(device_instance.connect(timeout=timeout))
+
+    else:
+        if not active_device_is_same_type(already_existing_device, device_factory):
+            raise TypeError(
+                f"Can't instantiate device of type {device_factory} with the same "
+                f"name as an existing device. Device name '{name}' already used for "
+                f"a(n) {type(already_existing_device)}."
+            )
+        device_instance = cast(T, already_existing_device)
+    if post_create:
+        post_create(device_instance)
+    return device_instance