diff --git a/src/numpydantic/ndarray.py b/src/numpydantic/ndarray.py
index 42fc3f8..8756ae0 100644
--- a/src/numpydantic/ndarray.py
+++ b/src/numpydantic/ndarray.py
@@ -125,14 +125,10 @@ class NDArrayMeta(_NDArrayMeta, implementation="NDArray"):
             check_type_names(dtype, dtype_per_name)
         elif isinstance(dtype_candidate, tuple):  # pragma: no cover
             dtype = tuple([cls._get_dtype(dt) for dt in dtype_candidate])
-        else:  # pragma: no cover
-            raise InvalidArgumentsError(
-                f"Unexpected argument '{dtype_candidate}', expecting"
-                " Structure[<StructureExpression>]"
-                " or Literal[<StructureExpression>]"
-                " or a dtype"
-                " or typing.Any."
-            )
+        else:
+            # arbitrary dtype - allow failure elsewhere :)
+            dtype = dtype_candidate
+
         return dtype
 
     def _dtype_to_str(cls, dtype: Any) -> str:
diff --git a/src/numpydantic/schema.py b/src/numpydantic/schema.py
index 9636190..552c27a 100644
--- a/src/numpydantic/schema.py
+++ b/src/numpydantic/schema.py
@@ -8,7 +8,7 @@ import json
 from typing import TYPE_CHECKING, Any, Callable, Optional, Union
 
 import numpy as np
-from pydantic import SerializationInfo
+from pydantic import BaseModel, SerializationInfo
 from pydantic_core import CoreSchema, core_schema
 from pydantic_core.core_schema import ListSchema, ValidationInfo
 
@@ -66,18 +66,18 @@ def _lol_dtype(dtype: DtypeType, _handler: _handler_type) -> CoreSchema:
     else:
         try:
             python_type = np_to_python[dtype]
-        except KeyError as e:  # pragma: no cover
+        except KeyError:  # pragma: no cover
             # this should pretty much only happen in downstream/3rd-party interfaces
             # that use interface-specific types. those need to provide mappings back
             # to base python types (making this more streamlined is TODO)
             if dtype in np_to_python.values():
                 # it's already a python type
                 python_type = dtype
+            elif issubclass(dtype, BaseModel):
+                python_type = dtype
             else:
-                raise ValueError(
-                    "dtype given in model does not have a corresponding python base "
-                    "type - add one to the `maps.np_to_python` dict"
-                ) from e
+                # does this need a warning?
+                python_type = Any
 
         if python_type in _UNSUPPORTED_TYPES:
             array_type = core_schema.any_schema()
diff --git a/tests/conftest.py b/tests/conftest.py
index 2292dd1..af3a48e 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -58,6 +58,10 @@ class ValidationCase(BaseModel):
         return Model
 
 
+class BasicModel(BaseModel):
+    x: int
+
+
 RGB_UNION: TypeAlias = Union[
     NDArray[Shape["* x, * y"], Number],
     NDArray[Shape["* x, * y, 3 r_g_b"], Number],
@@ -68,6 +72,7 @@ NUMBER: TypeAlias = NDArray[Shape["*, *, *"], Number]
 INTEGER: TypeAlias = NDArray[Shape["*, *, *"], Integer]
 FLOAT: TypeAlias = NDArray[Shape["*, *, *"], Float]
 STRING: TypeAlias = NDArray[Shape["*, *, *"], str]
+MODEL: TypeAlias = NDArray[Shape["*, *, *"], BasicModel]
 
 
 @pytest.fixture(
@@ -131,6 +136,8 @@ def shape_cases(request) -> ValidationCase:
         ValidationCase(annotation=STRING, dtype=str, passes=True),
         ValidationCase(annotation=STRING, dtype=int, passes=False),
         ValidationCase(annotation=STRING, dtype=float, passes=False),
+        ValidationCase(annotation=MODEL, dtype=BasicModel, passes=True),
+        ValidationCase(annotation=MODEL, dtype=int, passes=False),
     ],
     ids=[
         "float",
@@ -154,6 +161,8 @@ def shape_cases(request) -> ValidationCase:
         "str-str",
         "str-int",
         "str-float",
+        "model-model",
+        "model-int",
     ],
 )
 def dtype_cases(request) -> ValidationCase:
diff --git a/tests/test_interface/test_dask.py b/tests/test_interface/test_dask.py
index 6f7a8ac..fb1e4cb 100644
--- a/tests/test_interface/test_dask.py
+++ b/tests/test_interface/test_dask.py
@@ -4,7 +4,7 @@ import pytest
 import json
 
 import dask.array as da
-from pydantic import ValidationError
+from pydantic import BaseModel, ValidationError
 
 from numpydantic.interface import DaskInterface
 from numpydantic.exceptions import DtypeError, ShapeError
@@ -13,7 +13,10 @@ from tests.conftest import ValidationCase
 
 
 def dask_array(case: ValidationCase) -> da.Array:
-    return da.zeros(shape=case.shape, dtype=case.dtype, chunks=10)
+    if issubclass(case.dtype, BaseModel):
+        return da.full(shape=case.shape, fill_value=case.dtype(x=1), chunks=-1)
+    else:
+        return da.zeros(shape=case.shape, dtype=case.dtype, chunks=10)
 
 
 def _test_dask_case(case: ValidationCase):
diff --git a/tests/test_interface/test_hdf5.py b/tests/test_interface/test_hdf5.py
index f12bd87..78af785 100644
--- a/tests/test_interface/test_hdf5.py
+++ b/tests/test_interface/test_hdf5.py
@@ -20,6 +20,8 @@ def hdf5_array_case(case: ValidationCase, array_func) -> H5ArrayPath:
     Returns:
 
     """
+    if issubclass(case.dtype, BaseModel):
+        pytest.skip("hdf5 cant support arbitrary python objects")
     return array_func(case.shape, case.dtype)
 
 
diff --git a/tests/test_interface/test_numpy.py b/tests/test_interface/test_numpy.py
index 1ab6208..6a34b98 100644
--- a/tests/test_interface/test_numpy.py
+++ b/tests/test_interface/test_numpy.py
@@ -1,13 +1,16 @@
 import numpy as np
 import pytest
-from pydantic import ValidationError
+from pydantic import ValidationError, BaseModel
 from numpydantic.exceptions import DtypeError, ShapeError
 
 from tests.conftest import ValidationCase
 
 
 def numpy_array(case: ValidationCase) -> np.ndarray:
-    return np.zeros(shape=case.shape, dtype=case.dtype)
+    if issubclass(case.dtype, BaseModel):
+        return np.full(shape=case.shape, fill_value=case.dtype(x=1))
+    else:
+        return np.zeros(shape=case.shape, dtype=case.dtype)
 
 
 def _test_np_case(case: ValidationCase):
diff --git a/tests/test_interface/test_zarr.py b/tests/test_interface/test_zarr.py
index eab3e52..2e465f2 100644
--- a/tests/test_interface/test_zarr.py
+++ b/tests/test_interface/test_zarr.py
@@ -3,7 +3,9 @@ import json
 import pytest
 import zarr
 
-from pydantic import ValidationError
+from pydantic import BaseModel, ValidationError
+from numcodecs import Pickle
+
 
 from numpydantic.interface import ZarrInterface
 from numpydantic.interface.zarr import ZarrArrayPath
@@ -31,7 +33,19 @@ def nested_dir_array(tmp_output_dir_func) -> zarr.NestedDirectoryStore:
 
 
 def _zarr_array(case: ValidationCase, store) -> zarr.core.Array:
-    return zarr.zeros(shape=case.shape, dtype=case.dtype, store=store)
+    if issubclass(case.dtype, BaseModel):
+        pytest.skip(
+            f"Zarr can't handle objects properly at the moment, "
+            "see https://github.com/zarr-developers/zarr-python/issues/2081"
+        )
+        # return zarr.full(
+        #     shape=case.shape,
+        #     fill_value=case.dtype(x=1),
+        #     dtype=object,
+        #     object_codec=Pickle(),
+        # )
+    else:
+        return zarr.zeros(shape=case.shape, dtype=case.dtype, store=store)
 
 
 def _test_zarr_case(case: ValidationCase, store):
diff --git a/tests/test_ndarray.py b/tests/test_ndarray.py
index 7b512ef..9883c2a 100644
--- a/tests/test_ndarray.py
+++ b/tests/test_ndarray.py
@@ -266,6 +266,30 @@ def test_json_schema_dtype_builtin(dtype, expected, array_model):
         assert inner_type["type"] == expected
 
 
+def test_json_schema_dtype_model():
+    """
+    Pydantic models can be used in arrays as dtypes
+    """
+
+    class TestModel(BaseModel):
+        x: int
+        y: int
+        z: int
+
+    class MyModel(BaseModel):
+        array: NDArray[Shape["*, *"], TestModel]
+
+    schema = MyModel.model_json_schema()
+    # we should have a "$defs" with TestModel in it,
+    # and our array should be objects of that type
+    assert schema["properties"]["array"]["items"]["items"] == {
+        "$ref": "#/$defs/TestModel"
+    }
+    # we don't test pydantic' generic json schema model generation,
+    # just that one was defined
+    assert "TestModel" in schema["$defs"]
+
+
 def _recursive_array(schema):
     assert "$defs" in schema
     # get the key uses for the array