diff --git a/masque/file/dxf.py b/masque/file/dxf.py
index 4faac8c..56b0bc5 100644
--- a/masque/file/dxf.py
+++ b/masque/file/dxf.py
@@ -299,14 +299,14 @@ def _subpatterns_to_refs(block: Union[ezdxf.layouts.BlockLayout, ezdxf.layouts.M
             rotated_a = rotation_matrix_2d(-subpat.rotation) @ a
             rotated_b = rotation_matrix_2d(-subpat.rotation) @ b
             if rotated_a[1] == 0 and rotated_b[0] == 0:
-                attribs['column_count'] = subpat.a_count
-                attribs['row_count'] = subpat.b_count
+                attribs['column_count'] = rep.a_count
+                attribs['row_count'] = rep.b_count
                 attribs['column_spacing'] = rotated_a[0]
                 attribs['row_spacing'] = rotated_b[1]
                 block.add_blockref(encoded_name, subpat.offset, dxfattribs=attribs)
             elif rotated_a[0] == 0 and rotated_b[1] == 0:
-                attribs['column_count'] = subpat.b_count
-                attribs['row_count'] = subpat.a_count
+                attribs['column_count'] = rep.b_count
+                attribs['row_count'] = rep.a_count
                 attribs['column_spacing'] = rotated_b[0]
                 attribs['row_spacing'] = rotated_a[1]
                 block.add_blockref(encoded_name, subpat.offset, dxfattribs=attribs)
diff --git a/masque/file/gdsii.py b/masque/file/gdsii.py
index 4c2198c..0be8e3e 100644
--- a/masque/file/gdsii.py
+++ b/masque/file/gdsii.py
@@ -365,8 +365,8 @@ def _ref_to_subpat(element: Union[gdsii.elements.SRef,
     if isinstance(element, gdsii.elements.ARef):
         a_count = element.cols
         b_count = element.rows
-        a_vector = (element.xy[1] - offset) / counts[0]
-        b_vector = (element.xy[2] - offset) / counts[1]
+        a_vector = (element.xy[1] - offset) / a_count
+        b_vector = (element.xy[2] - offset) / b_count
         repetition = Grid(a_vector=a_vector, b_vector=b_vector,
                           a_count=a_count, b_count=b_count)
 
@@ -389,9 +389,10 @@ def _subpatterns_to_refs(subpatterns: List[SubPattern]
 
         # Note: GDS mirrors first and rotates second
         mirror_across_x, extra_angle = normalize_mirror(subpat.mirrored)
-        ref: Union[gdsii.elements.SRef, gdsii.elements.ARef]
-
         rep = subpat.repetition
+
+        new_refs: List[Union[gdsii.elements.SRef, gdsii.elements.ARef]]
+        ref: Union[gdsii.elements.SRef, gdsii.elements.ARef]
         if isinstance(rep, Grid):
             xy = numpy.array(subpat.offset) + [
                   [0, 0],
diff --git a/masque/file/oasis.py b/masque/file/oasis.py
index 775cff7..981d1e0 100644
--- a/masque/file/oasis.py
+++ b/masque/file/oasis.py
@@ -469,7 +469,7 @@ def _placement_to_subpat(placement: fatrec.Placement) -> SubPattern:
        'identifier': (name,),
        }
 
-    mrep: Repetition
+    mrep: Optional[Repetition]
     rep = placement.repetition
     if isinstance(rep, fatamorgana.GridRepetition):
         mrep = Grid(a_vector=rep.a_vector,
@@ -477,8 +477,10 @@ def _placement_to_subpat(placement: fatrec.Placement) -> SubPattern:
                     a_count=rep.a_count,
                     b_count=rep.b_count)
     elif isinstance(rep, fatamorgana.ArbitraryRepetition):
-        mrep = Arbitrary(numpy.cumsum(numpy.column_stack((rep.x_displacements,
-                                                          rep.y_displacements))))
+        displacements = numpy.cumsum(numpy.column_stack((rep.x_displacements,
+                                                         rep.y_displacements)))
+        displacements = numpy.vstack(([0, 0], displacements))
+        mrep = Arbitrary(displacements)
     elif rep is None:
         mrep = None
 
@@ -510,8 +512,10 @@ def _subpatterns_to_refs(subpatterns: List[SubPattern]
                               b_count=numpy.round(rep.b_count).astype(int))
         elif isinstance(rep, Arbitrary):
             diffs = numpy.diff(rep.displacements, axis=0)
-            args['repetition'] = fatamorgana.ArbitraryRepetition(
-                                    numpy.round(diffs).astype(int))
+            diff_ints = numpy.round(diffs).astype(int)
+            args['repetition'] = fatamorgana.ArbitraryRepetition(diff_ints[:, 0], diff_ints[:, 1])
+            args['x'] += rep.displacements[0, 0]
+            args['y'] += rep.displacements[0, 1]
         else:
             assert(rep is None)
 
diff --git a/masque/repetition.py b/masque/repetition.py
index 737fb33..5707a50 100644
--- a/masque/repetition.py
+++ b/masque/repetition.py
@@ -217,7 +217,7 @@ class Grid(LockableImpl, Repetition, metaclass=AutoSlots):
 
         corners = ((0, 0), a_extent, b_extent, a_extent + b_extent)
         xy_min = numpy.min(corners, axis=0)
-        xy_max = numpy.min(corners, axis=0)
+        xy_max = numpy.max(corners, axis=0)
         return numpy.array((xy_min, xy_max))
 
     def scale_by(self, c: float) -> 'Grid':
@@ -298,9 +298,6 @@ class Arbitrary(LockableImpl, Repetition, metaclass=AutoSlots):
           of the instances.
     """
 
-    locked: bool
-    """ If `True`, disallows changes to the object. """
-
     @property
     def displacements(self) -> numpy.ndarray:
         return self._displacements
@@ -311,6 +308,18 @@ class Arbitrary(LockableImpl, Repetition, metaclass=AutoSlots):
         val = numpy.sort(val.view([('', val.dtype)] * val.shape[1]), 0).view(val.dtype)    # sort rows
         self._displacements = val
 
+    def __init__(self,
+                 displacements: numpy.ndarray,
+                 locked: bool = False,):
+        """
+        Args:
+            displacements: List of vectors (Nx2 ndarray) specifying displacements.
+            locked: Whether the object is locked after initialization.
+        """
+        object.__setattr__(self, 'locked', False)
+        self.displacements = displacements
+        self.locked = locked
+
     def lock(self) -> 'Arbitrary':
         """
         Lock the object, disallowing changes.
@@ -343,3 +352,56 @@ class Arbitrary(LockableImpl, Repetition, metaclass=AutoSlots):
         if self.locked != other.locked:
             return False
         return numpy.array_equal(self.displacements, other.displacements)
+
+    def rotate(self, rotation: float) -> 'Arbitrary':
+        """
+        Rotate dispacements (around (0, 0))
+
+        Args:
+            rotation: Angle to rotate by (counterclockwise, radians)
+
+        Returns:
+            self
+        """
+        self.displacements = numpy.dot(rotation_matrix_2d(rotation), self.displacements.T).T
+        return self
+
+    def mirror(self, axis: int) -> 'Arbitrary':
+        """
+        Mirror the displacements across an axis.
+
+        Args:
+            axis: Axis to mirror across.
+                (0: mirror across x-axis, 1: mirror across y-axis)
+
+        Returns:
+            self
+        """
+        self.displacements[1-axis] *= -1
+        return self
+
+    def get_bounds(self) -> Optional[numpy.ndarray]:
+        """
+        Return a `numpy.ndarray` containing `[[x_min, y_min], [x_max, y_max]]`, corresponding to the
+         extent of the `displacements` in each dimension.
+
+        Returns:
+            `[[x_min, y_min], [x_max, y_max]]` or `None`
+        """
+        xy_min = numpy.min(self.displacements, axis=0)
+        xy_max = numpy.max(self.displacements, axis=0)
+        return numpy.array((xy_min, xy_max))
+
+    def scale_by(self, c: float) -> 'Arbitrary':
+        """
+        Scale the displacements by a factor
+
+        Args:
+            c: scaling factor
+
+        Returns:
+            self
+        """
+        self.displacements *= c
+        return self
+
diff --git a/masque/subpattern.py b/masque/subpattern.py
index 7243e5e..e898349 100644
--- a/masque/subpattern.py
+++ b/masque/subpattern.py
@@ -35,27 +35,12 @@ class SubPattern(PositionableImpl, DoseableImpl, RotatableImpl, ScalableImpl, Mi
     _pattern: Optional['Pattern']
     """ The `Pattern` being instanced """
 
-#    _offset: numpy.ndarray
-#    """ (x, y) offset for the instance """
-
-#    _rotation: float
-#    """ rotation for the instance, radians counterclockwise """
-
-#    _dose: float
-#    """ dose factor for the instance """
-
-#    _scale: float
-#    """ scale factor for the instance """
-
     _mirrored: numpy.ndarray        # ndarray[bool]
     """ Whether to mirror the instance across the x and/or y axes. """
 
     identifier: Tuple[Any, ...]
     """ Arbitrary identifier, used internally by some `masque` functions. """
 
-#    locked: bool
-#    """ If `True`, disallows changes to the SubPattern"""
-
     def __init__(self,
                  pattern: Optional['Pattern'],
                  offset: vector2 = (0.0, 0.0),
@@ -79,7 +64,6 @@ class SubPattern(PositionableImpl, DoseableImpl, RotatableImpl, ScalableImpl, Mi
             identifier: Arbitrary tuple, used internally by some `masque` functions.
         """
         LockableImpl.unlock(self)
-#        object.__setattr__(self, 'locked', False)
         self.identifier = identifier
         self.pattern = pattern
         self.offset = offset
@@ -146,9 +130,9 @@ class SubPattern(PositionableImpl, DoseableImpl, RotatableImpl, ScalableImpl, Mi
         pattern.translate_elements(self.offset)
         pattern.scale_element_doses(self.dose)
 
-        if pattern.repetition is not None:
-            combined = type(pat)(name='__repetition__')
-            for dd in pattern.repetition.displacements:
+        if self.repetition is not None:
+            combined = type(pattern)(name='__repetition__')
+            for dd in self.repetition.displacements:
                 temp_pat = pattern.deepcopy()
                 temp_pat.translate_elements(dd)
                 combined.append(temp_pat)
diff --git a/masque/traits/doseable.py b/masque/traits/doseable.py
index ded93fa..4b9daf3 100644
--- a/masque/traits/doseable.py
+++ b/masque/traits/doseable.py
@@ -28,10 +28,10 @@ class Doseable(metaclass=ABCMeta):
         """
         pass
 
-    @dose.setter
-    @abstractmethod
-    def dose(self, val: float):
-        pass
+#    @dose.setter
+#    @abstractmethod
+#    def dose(self, val: float):
+#        pass
 
     '''
     ---- Methods
diff --git a/masque/traits/layerable.py b/masque/traits/layerable.py
index 4cf0b1f..5382450 100644
--- a/masque/traits/layerable.py
+++ b/masque/traits/layerable.py
@@ -25,12 +25,12 @@ class Layerable(metaclass=ABCMeta):
         """
         Layer number or name (int, tuple of ints, or string)
         """
-        return self._layer
+        pass
 
-    @layer.setter
-    @abstractmethod
-    def layer(self, val: layer_t):
-        self._layer = val
+#    @layer.setter
+#    @abstractmethod
+#    def layer(self, val: layer_t):
+#        pass
 
     '''
     ---- Methods
diff --git a/masque/traits/lockable.py b/masque/traits/lockable.py
index e0ea24e..cc12760 100644
--- a/masque/traits/lockable.py
+++ b/masque/traits/lockable.py
@@ -19,18 +19,6 @@ class Lockable(metaclass=ABCMeta):
     '''
     ---- Methods
     '''
-    def set_dose(self: T, dose: float) -> T:
-        """
-        Set the dose
-
-        Args:
-            dose: new value for dose
-
-        Returns:
-            self
-        """
-        pass
-
     def lock(self: T) -> T:
         """
         Lock the object, disallowing further changes
diff --git a/masque/traits/mirrorable.py b/masque/traits/mirrorable.py
index 76226c4..1e10800 100644
--- a/masque/traits/mirrorable.py
+++ b/masque/traits/mirrorable.py
@@ -6,7 +6,7 @@ import numpy
 from ..error import PatternError, PatternLockedError
 
 T = TypeVar('T', bound='Mirrorable')
-T = TypeVar('T', bound='MirrorableImpl')
+#I = TypeVar('I', bound='MirrorableImpl')
 
 
 class Mirrorable(metaclass=ABCMeta):
diff --git a/masque/traits/positionable.py b/masque/traits/positionable.py
index 3669a7e..4db6880 100644
--- a/masque/traits/positionable.py
+++ b/masque/traits/positionable.py
@@ -30,10 +30,10 @@ class Positionable(metaclass=ABCMeta):
         """
         pass
 
-    @offset.setter
-    @abstractmethod
-    def offset(self, val: vector2):
-        pass
+#    @offset.setter
+#    @abstractmethod
+#    def offset(self, val: vector2):
+#        pass
 
     '''
     --- Abstract methods
diff --git a/masque/traits/repeatable.py b/masque/traits/repeatable.py
index 1f2a99b..3971a94 100644
--- a/masque/traits/repeatable.py
+++ b/masque/traits/repeatable.py
@@ -1,4 +1,4 @@
-from typing import List, Tuple, Callable, TypeVar, Optional
+from typing import List, Tuple, Callable, TypeVar, Optional, TYPE_CHECKING
 from abc import ABCMeta, abstractmethod
 import copy
 import numpy
@@ -6,6 +6,10 @@ import numpy
 from ..error import PatternError, PatternLockedError
 
 
+if TYPE_CHECKING:
+    from ..repetition import Repetition
+
+
 T = TypeVar('T', bound='Repeatable')
 I = TypeVar('I', bound='RepeatableImpl')
 
@@ -27,14 +31,15 @@ class Repeatable(metaclass=ABCMeta):
         """
         pass
 
-    @repetition.setter
-    @abstractmethod
-    def repetition(self, repetition: Optional['Repetition']):
-        pass
+#    @repetition.setter
+#    @abstractmethod
+#    def repetition(self, repetition: Optional['Repetition']):
+#        pass
 
     '''
     ---- Methods
     '''
+    @abstractmethod
     def set_repetition(self: T, repetition: Optional['Repetition']) -> T:
         """
         Set the repetition
@@ -74,6 +79,6 @@ class RepeatableImpl(Repeatable, metaclass=ABCMeta):
     '''
     ---- Non-abstract methods
     '''
-    def set_repetition(self: I, repetition: 'Repetition') -> I:
+    def set_repetition(self: I, repetition: Optional['Repetition']) -> I:
         self.repetition = repetition
         return self