diff --git a/graphene/types/tests/test_mutation.py b/graphene/types/tests/test_mutation.py
index 2af6f4fd..d60f4950 100644
--- a/graphene/types/tests/test_mutation.py
+++ b/graphene/types/tests/test_mutation.py
@@ -44,15 +44,30 @@ def test_mutation_raises_exception_if_no_mutate():
 
 
 def test_mutation_execution():
+    def with_metadata(gql_type, data):
+        setattr(gql_type, 'metadata', data)
+        return gql_type
+
     class CreateUser(Mutation):
         class Input:
             name = String()
+            metadata = with_metadata(String(), 'service_key')
+
+        _Input = Input
 
         name = String()
+        external = String()
 
-        def mutate(self, args, context, info):
+        @classmethod
+        def mutate(cls, root, args, context, info):
             name = args.get('name')
-            return CreateUser(name=name)
+            external_data = {
+                'service_key': 'new_data'
+            }
+
+            metadata_type = dict(vars(cls._Input))['metadata']
+            data = external_data[getattr(metadata_type, 'metadata')]
+            return CreateUser(name=name, external=data)
 
     class Query(ObjectType):
         a = String()
@@ -64,12 +79,14 @@ def test_mutation_execution():
     result = schema.execute(''' mutation mymutation {
         createUser(name:"Peter") {
             name
+            external
         }
     }
     ''')
     assert not result.errors
     assert result.data == {
         'createUser': {
-            'name': "Peter"
+            'name': 'Peter',
+            'external': 'new_data',
         }
     }
diff --git a/graphene/types/tests/test_query.py b/graphene/types/tests/test_query.py
index 4f9d8810..742f3c19 100644
--- a/graphene/types/tests/test_query.py
+++ b/graphene/types/tests/test_query.py
@@ -56,6 +56,36 @@ def test_query_wrong_default_value():
     assert executed.data == {'hello': None}
 
 
+def test_query_unmounted_type_with_custom_attributes():
+    def set_custom_metadata(gql_type):
+        setattr(gql_type, 'metadata', 'some_key')
+        return gql_type
+
+    class MyType(ObjectType):
+        field = set_custom_metadata(String())
+
+        @classmethod
+        def from_metadata(cls):
+            my_type = cls()
+            external_data = {
+                'some_key': 'my_data'
+            }
+            for field_name, field_value in cls._meta.fields.items():
+                data = external_data[getattr(field_value, 'metadata')]
+                setattr(my_type, field_name, data)
+
+            return my_type
+
+    class Query(ObjectType):
+        hello = Field(MyType, resolver=lambda *_: MyType.from_metadata())
+
+    hello_schema = Schema(Query)
+
+    executed = hello_schema.execute('{ hello { field } }')
+    assert not executed.errors
+    assert executed.data == {'hello': {'field': 'my_data'}}
+
+
 def test_query_default_value_ignored_by_resolver():
     class MyType(ObjectType):
         field = String()
diff --git a/graphene/types/unmountedtype.py b/graphene/types/unmountedtype.py
index c9b36631..d3e5c98a 100644
--- a/graphene/types/unmountedtype.py
+++ b/graphene/types/unmountedtype.py
@@ -19,34 +19,52 @@ class UnmountedType(OrderedType):
         super(UnmountedType, self).__init__()
         self.args = args
         self.kwargs = kwargs
+        self.custom_attributes = {}
 
     def get_type(self):
         raise NotImplementedError("get_type not implemented in {}".format(self))
 
+    def __setattr__(self, name, value):
+        if hasattr(self, 'custom_attributes'):
+            self.custom_attributes[name] = value
+        OrderedType.__setattr__(self, name, value)
+
     def Field(self):  # noqa: N802
         '''
         Mount the UnmountedType as Field
         '''
         from .field import Field
-        return Field(
+        f = Field(
             self.get_type(),
             *self.args,
             _creation_counter=self.creation_counter,
             **self.kwargs
         )
 
+        if hasattr(self, 'custom_attributes'):
+            for name, value in self.custom_attributes.items():
+                setattr(f, name, value)
+
+        return f
+
     def InputField(self):  # noqa: N802
         '''
         Mount the UnmountedType as InputField
         '''
         from .inputfield import InputField
-        return InputField(
+        f = InputField(
             self.get_type(),
             *self.args,
             _creation_counter=self.creation_counter,
             **self.kwargs
         )
 
+        if hasattr(self, 'custom_attributes'):
+            for name, value in self.custom_attributes.items():
+                setattr(f, name, value)
+
+        return f
+
     def Argument(self):  # noqa: N802
         '''
         Mount the UnmountedType as Argument