diff --git a/masque/builder/tools.py b/masque/builder/tools.py
index 0e08674..1ffaa4d 100644
--- a/masque/builder/tools.py
+++ b/masque/builder/tools.py
@@ -3,7 +3,7 @@ Tools are objects which dynamically generate simple single-use devices (e.g. wir
 
 # TODO document all tools
 """
-from typing import Literal, Any, Self, cast, TYPE_CHECKING
+from typing import Literal, Any, Self, cast
 from collections.abc import Sequence, Callable
 from abc import ABCMeta  # , abstractmethod     # TODO any way to make Tool ok with implementing only one method?
 from dataclasses import dataclass
@@ -593,7 +593,7 @@ class AutoTool(Tool, metaclass=ABCMeta):
         success = False
         # If ccw is None, we don't need a bend, but we still loop to reuse the logic.
         # We'll use a dummy loop if bends is empty and ccw is None.
-        bends = cast(list[AutoTool.Bend | None], self.bends)
+        bends = cast('list[AutoTool.Bend | None]', self.bends)
         if ccw is None and not bends:
             bends += [None]
 
@@ -613,7 +613,7 @@ class AutoTool(Tool, metaclass=ABCMeta):
 
                 out_ptype_pair = (
                     'unk' if out_ptype is None else out_ptype,
-                    straight.ptype if ccw is None else cast(AutoTool.Bend, bend).out_port.ptype
+                    straight.ptype if ccw is None else cast('AutoTool.Bend', bend).out_port.ptype
                     )
                 out_transition = self.transitions.get(out_ptype_pair, None)
                 otrans_dxy = self._otransition2dxy(out_transition, bend_angle)
diff --git a/masque/pattern.py b/masque/pattern.py
index 42f9ab4..94555cc 100644
--- a/masque/pattern.py
+++ b/masque/pattern.py
@@ -2,7 +2,7 @@
   Object representing a one multi-layer lithographic layout.
   A single level of hierarchical references is included.
 """
-from typing import cast, Self, Any, TypeVar
+from typing import cast, Self, Any, TypeVar, TYPE_CHECKING
 from collections.abc import Sequence, Mapping, MutableMapping, Iterable, Callable
 import copy
 import logging
@@ -25,6 +25,9 @@ from .error import PatternError, PortError
 from .traits import AnnotatableImpl, Scalable, Mirrorable, Rotatable, Positionable, Repeatable, Bounded
 from .ports import Port, PortList
 
+if TYPE_CHECKING:
+    from .traits import Flippable
+
 
 logger = logging.getLogger(__name__)
 
diff --git a/masque/ports.py b/masque/ports.py
index 740636e..f2651de 100644
--- a/masque/ports.py
+++ b/masque/ports.py
@@ -11,7 +11,7 @@ import numpy
 from numpy import pi
 from numpy.typing import ArrayLike, NDArray
 
-from .traits import PositionableImpl, Rotatable, PivotableImpl, Copyable, Mirrorable, Flippable
+from .traits import PositionableImpl, Rotatable, PivotableImpl, Copyable, Flippable
 from .utils import rotate_offsets_around, rotation_matrix_2d
 from .error import PortError, format_stacktrace
 
diff --git a/masque/shapes/shape.py b/masque/shapes/shape.py
index 43aa222..269c460 100644
--- a/masque/shapes/shape.py
+++ b/masque/shapes/shape.py
@@ -6,7 +6,7 @@ import numpy
 from numpy.typing import NDArray, ArrayLike
 
 from ..traits import (
-    Rotatable, Mirrorable, Copyable, Scalable, FlippableImpl,
+    Rotatable, Copyable, Scalable, FlippableImpl,
     Positionable, Pivotable, PivotableImpl, RepeatableImpl, AnnotatableImpl,
     )
 
diff --git a/masque/traits/mirrorable.py b/masque/traits/mirrorable.py
index 2ff486a..9b4072b 100644
--- a/masque/traits/mirrorable.py
+++ b/masque/traits/mirrorable.py
@@ -1,14 +1,15 @@
-from typing import Self, Any, TYPE_CHECKING, cast
+from typing import Self, cast, TYPE_CHECKING
 from abc import ABCMeta, abstractmethod
 
 import numpy
-from numpy.typing import ArrayLike, NDArray
+from numpy.typing import NDArray
 
 from ..error import MasqueError
-
-from .positionable import Positionable
 from .repeatable import Repeatable
 
+if TYPE_CHECKING:
+    from .positionable import Positionable
+
 
 class Mirrorable(metaclass=ABCMeta):
     """