diff --git a/examples/tutorial/pcgen.py b/examples/tutorial/pcgen.py
index 023079c..c265f64 100644
--- a/examples/tutorial/pcgen.py
+++ b/examples/tutorial/pcgen.py
@@ -233,8 +233,8 @@ def ln_shift_defect(
 
     # Shift holes
     # Expand shifts as necessary
-    tmp_a = numpy.asarray(shifts_a)
-    tmp_r = numpy.asarray(shifts_r)
+    tmp_a = numpy.array(shifts_a)
+    tmp_r = numpy.array(shifts_r)
     n_shifted = max(tmp_a.size, tmp_r.size)
 
     shifts_a = numpy.ones(n_shifted)
diff --git a/masque/abstract.py b/masque/abstract.py
index 248c8a5..e3ab46e 100644
--- a/masque/abstract.py
+++ b/masque/abstract.py
@@ -97,7 +97,7 @@ class Abstract(PortList):
         Returns:
             self
         """
-        pivot = numpy.asarray(pivot, dtype=float)
+        pivot = numpy.array(pivot)
         self.translate_ports(-pivot)
         self.rotate_ports(rotation)
         self.rotate_port_offsets(rotation)
diff --git a/masque/file/dxf.py b/masque/file/dxf.py
index dc3d6f3..aa73279 100644
--- a/masque/file/dxf.py
+++ b/masque/file/dxf.py
@@ -212,9 +212,9 @@ def _read_block(block: ezdxf.layouts.BlockLayout | ezdxf.layouts.Modelspace) ->
     for element in block:
         if isinstance(element, LWPolyline | Polyline):
             if isinstance(element, LWPolyline):
-                points = numpy.asarray(element.get_points())
+                points = numpy.array(element.get_points())
             elif isinstance(element, Polyline):
-                points = numpy.asarray(element.points())[:, :2]
+                points = numpy.array(element.points())[:, :2]
             attr = element.dxfattribs()
             layer = attr.get('layer', DEFAULT_LAYER)
 
@@ -241,7 +241,7 @@ def _read_block(block: ezdxf.layouts.BlockLayout | ezdxf.layouts.Modelspace) ->
 
         elif isinstance(element, Text):
             args = dict(
-                offset=numpy.asarray(element.get_placement()[1])[:2],
+                offset=numpy.array(element.get_placement()[1])[:2],
                 layer=element.dxfattribs().get('layer', DEFAULT_LAYER),
                 )
             string = element.dxfattribs().get('text', '')
@@ -262,7 +262,7 @@ def _read_block(block: ezdxf.layouts.BlockLayout | ezdxf.layouts.Modelspace) ->
             mirrored, extra_angle = normalize_mirror((yscale < 0, xscale < 0))
             rotation = numpy.deg2rad(attr.get('rotation', 0)) + extra_angle
 
-            offset = numpy.asarray(attr.get('insert', (0, 0, 0)))[:2]
+            offset = numpy.array(attr.get('insert', (0, 0, 0)))[:2]
 
             args = dict(
                 target=attr.get('name', None),
diff --git a/masque/file/gdsii.py b/masque/file/gdsii.py
index 71ea94f..11e1574 100644
--- a/masque/file/gdsii.py
+++ b/masque/file/gdsii.py
@@ -357,7 +357,7 @@ def _mrefs_to_grefs(refs: dict[str | None, list[Ref]]) -> list[klamath.library.R
             if isinstance(rep, Grid):
                 b_vector = rep.b_vector if rep.b_vector is not None else numpy.zeros(2)
                 b_count = rep.b_count if rep.b_count is not None else 1
-                xy = numpy.asarray(ref.offset) + numpy.array([
+                xy = numpy.array(ref.offset) + numpy.array([
                     [0.0, 0.0],
                     rep.a_vector * rep.a_count,
                     b_vector * b_count,
diff --git a/masque/file/svg.py b/masque/file/svg.py
index 148f6d4..8c4b43d 100644
--- a/masque/file/svg.py
+++ b/masque/file/svg.py
@@ -154,7 +154,7 @@ def poly2path(vertices: ArrayLike) -> str:
     Returns:
         SVG path-string.
     """
-    verts = numpy.asarray(vertices)
+    verts = numpy.array(vertices, copy=False)
     commands = 'M{:g},{:g} '.format(verts[0][0], verts[0][1])      # noqa: UP032
     for vertex in verts[1:]:
         commands += 'L{:g},{:g}'.format(vertex[0], vertex[1])      # noqa: UP032
diff --git a/masque/label.py b/masque/label.py
index 711ef35..7eb9068 100644
--- a/masque/label.py
+++ b/masque/label.py
@@ -49,7 +49,7 @@ class Label(PositionableImpl, RepeatableImpl, AnnotatableImpl, Bounded, Pivotabl
             annotations: annotations_t | None = None,
             ) -> None:
         self.string = string
-        self.offset = numpy.array(offset, dtype=float)
+        self.offset = numpy.array(offset, dtype=float, copy=True)
         self.repetition = repetition
         self.annotations = annotations if annotations is not None else {}
 
@@ -94,7 +94,7 @@ class Label(PositionableImpl, RepeatableImpl, AnnotatableImpl, Bounded, Pivotabl
         Returns:
             self
         """
-        pivot = numpy.asarray(pivot, dtype=float)
+        pivot = numpy.array(pivot, dtype=float)
         self.translate(-pivot)
         self.offset = numpy.dot(rotation_matrix_2d(rotation), self.offset)
         self.translate(+pivot)
diff --git a/masque/library.py b/masque/library.py
index 11a3c1e..9771eaf 100644
--- a/masque/library.py
+++ b/masque/library.py
@@ -460,7 +460,7 @@ class ILibraryView(Mapping[str, 'Pattern'], metaclass=ABCMeta):
         if transform is None or transform is True:
             transform = numpy.zeros(4)
         elif transform is not False:
-            transform = numpy.asarray(transform, dtype=float)
+            transform = numpy.array(transform, dtype=float, copy=False)
 
         original_pattern = pattern
 
diff --git a/masque/pattern.py b/masque/pattern.py
index 1816762..47f64c5 100644
--- a/masque/pattern.py
+++ b/masque/pattern.py
@@ -690,7 +690,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         Returns:
             self
         """
-        pivot = numpy.asarray(pivot, dtype=float)
+        pivot = numpy.array(pivot)
         self.translate_elements(-pivot)
         self.rotate_elements(rotation)
         self.rotate_element_centers(rotation)
@@ -1023,7 +1023,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         if self.has_refs() and library is None:
             raise PatternError('Must provide a library when visualizing a pattern with refs')
 
-        offset = numpy.asarray(offset, dtype=float)
+        offset = numpy.array(offset, dtype=float)
 
         if not overdraw:
             figure = pyplot.figure()
diff --git a/masque/repetition.py b/masque/repetition.py
index a365909..68b6b19 100644
--- a/masque/repetition.py
+++ b/masque/repetition.py
@@ -156,11 +156,12 @@ class Grid(Repetition):
 
     @a_vector.setter
     def a_vector(self, val: ArrayLike) -> None:
-        val = numpy.array(val, dtype=float)
+        if not isinstance(val, numpy.ndarray):
+            val = numpy.array(val, dtype=float)
 
         if val.size != 2:
             raise PatternError('a_vector must be convertible to size-2 ndarray')
-        self._a_vector = val.flatten()
+        self._a_vector = val.flatten().astype(float)
 
     # b_vector property
     @property
@@ -169,7 +170,8 @@ class Grid(Repetition):
 
     @b_vector.setter
     def b_vector(self, val: ArrayLike) -> None:
-        val = numpy.array(val, dtype=float)
+        if not isinstance(val, numpy.ndarray):
+            val = numpy.array(val, dtype=float, copy=True)
 
         if val.size != 2:
             raise PatternError('b_vector must be convertible to size-2 ndarray')
@@ -332,9 +334,9 @@ class Arbitrary(Repetition):
 
     @displacements.setter
     def displacements(self, val: ArrayLike) -> None:
-        vala = numpy.array(val, dtype=float)
-        order = numpy.lexsort(vala.T[::-1])     # sortrows
-        self._displacements = vala[order]
+        vala: NDArray[numpy.float64] = numpy.array(val, dtype=float)
+        vala = numpy.sort(vala.view([('', vala.dtype)] * vala.shape[1]), 0).view(vala.dtype)    # sort rows
+        self._displacements = vala
 
     def __init__(
             self,
diff --git a/masque/shapes/arc.py b/masque/shapes/arc.py
index eb565bf..8d14f0f 100644
--- a/masque/shapes/arc.py
+++ b/masque/shapes/arc.py
@@ -472,7 +472,7 @@ class Arc(Shape):
                 a1 += sign * 2 * pi
 
             a.append((a0, a1))
-        return numpy.array(a, dtype=float)
+        return numpy.array(a)
 
     def __repr__(self) -> str:
         angles = f' a°{numpy.rad2deg(self.angles)}'
diff --git a/masque/shapes/path.py b/masque/shapes/path.py
index aaac0d2..dfd89f1 100644
--- a/masque/shapes/path.py
+++ b/masque/shapes/path.py
@@ -33,7 +33,8 @@ class Path(Shape):
     A path, consisting of a bunch of vertices (Nx2 ndarray), a width, an end-cap shape,
         and an offset.
 
-    Note that the setter for `Path.vertices` will create a copy of the passed vertex coordinates.
+    Note that the setter for `Path.vertices` may (but may not) create a copy of the
+      passed vertex coordinates. See `numpy.array(..., copy=False)` for details.
 
     A normalized_form(...) is available, but can be quite slow with lots of vertices.
     """
@@ -117,7 +118,8 @@ class Path(Shape):
         """
         Vertices of the path (Nx2 ndarray: `[[x0, y0], [x1, y1], ...]`
 
-        When setting, note that a copy of the provided vertices will be made.
+        When setting, note that a copy of the provided vertices may or may not be made,
+        following the rules from `numpy.array(.., copy=False)`.
         """
         return self._vertices
 
diff --git a/masque/shapes/polygon.py b/masque/shapes/polygon.py
index 1e0352f..f6add4d 100644
--- a/masque/shapes/polygon.py
+++ b/masque/shapes/polygon.py
@@ -20,8 +20,8 @@ class Polygon(Shape):
     A polygon, consisting of a bunch of vertices (Nx2 ndarray) which specify an
        implicitly-closed boundary, and an offset.
 
-    Note that the setter for `Polygon.vertices` may creates a copy of the
-      passed vertex coordinates.
+    Note that the setter for `Polygon.vertices` may (but may not) create a copy of the
+      passed vertex coordinates. See `numpy.array(..., copy=False)` for details.
 
     A `normalized_form(...)` is available, but can be quite slow with lots of vertices.
     """
@@ -40,7 +40,8 @@ class Polygon(Shape):
         """
         Vertices of the polygon (Nx2 ndarray: `[[x0, y0], [x1, y1], ...]`)
 
-        When setting, note that a copy of the provided vertices will be made,
+        When setting, note that a copy of the provided vertices may or may not be made,
+        following the rules from `numpy.array(.., copy=False)`.
         """
         return self._vertices
 
diff --git a/masque/shapes/text.py b/masque/shapes/text.py
index e936796..fa0038b 100644
--- a/masque/shapes/text.py
+++ b/masque/shapes/text.py
@@ -230,8 +230,7 @@ def get_char_as_polygons(
     outline = slot.outline
 
     start = 0
-    all_verts_list = []
-    all_codes = []
+    all_verts_list, all_codes = [], []
     for end in outline.contours:
         points = outline.points[start:end + 1]
         points.append(points[0])
diff --git a/masque/traits/mirrorable.py b/masque/traits/mirrorable.py
index 6d4ec3c..bb7f011 100644
--- a/masque/traits/mirrorable.py
+++ b/masque/traits/mirrorable.py
@@ -60,7 +60,7 @@ class Mirrorable(metaclass=ABCMeta):
 #    def mirrored(self, val: Sequence[bool]) -> None:
 #        if is_scalar(val):
 #            raise MasqueError('Mirrored must be a 2-element list of booleans')
-#        self._mirrored = numpy.array(val, dtype=bool)
+#        self._mirrored = numpy.array(val, dtype=bool, copy=True)
 #
 #    #
 #    # Methods
diff --git a/masque/traits/positionable.py b/masque/traits/positionable.py
index 66e6e7d..2b9c02e 100644
--- a/masque/traits/positionable.py
+++ b/masque/traits/positionable.py
@@ -81,11 +81,12 @@ class PositionableImpl(Positionable, metaclass=ABCMeta):
 
     @offset.setter
     def offset(self, val: ArrayLike) -> None:
-        val = numpy.array(val, dtype=float)
+        if not isinstance(val, numpy.ndarray) or val.dtype != numpy.float64:
+            val = numpy.array(val, dtype=float)
 
         if val.size != 2:
             raise MasqueError('Offset must be convertible to size-2 ndarray')
-        self._offset = val.flatten()
+        self._offset = val.flatten()        # type: ignore
 
     #
     # Methods
diff --git a/masque/traits/rotatable.py b/masque/traits/rotatable.py
index f873ce4..45caa31 100644
--- a/masque/traits/rotatable.py
+++ b/masque/traits/rotatable.py
@@ -112,7 +112,7 @@ class PivotableImpl(Pivotable, metaclass=ABCMeta):
     """ `[x_offset, y_offset]` """
 
     def rotate_around(self, pivot: ArrayLike, rotation: float) -> Self:
-        pivot = numpy.asarray(pivot, dtype=float)
+        pivot = numpy.array(pivot, dtype=float)
         cast(Positionable, self).translate(-pivot)
         cast(Rotatable, self).rotate(rotation)
         self.offset = numpy.dot(rotation_matrix_2d(rotation), self.offset)      # type: ignore # mypy#3004
diff --git a/masque/utils/pack2d.py b/masque/utils/pack2d.py
index ce6b006..5de9728 100644
--- a/masque/utils/pack2d.py
+++ b/masque/utils/pack2d.py
@@ -38,8 +38,8 @@ def maxrects_bssf(
     Raises:
         MasqueError if `allow_rejects` is `True` but some `rects` could not be placed.
     """
-    regions = numpy.asarray(containers, dtype=float)
-    rect_sizes = numpy.asarray(rects, dtype=float)
+    regions = numpy.array(containers, copy=False, dtype=float)
+    rect_sizes = numpy.array(rects, copy=False, dtype=float)
     rect_locs = numpy.zeros_like(rect_sizes)
     rejected_inds = set()
 
@@ -139,8 +139,8 @@ def guillotine_bssf_sas(
     Raises:
         MasqueError if `allow_rejects` is `True` but some `rects` could not be placed.
     """
-    regions = numpy.asarray(containers, dtype=float)
-    rect_sizes = numpy.asarray(rects, dtype=float)
+    regions = numpy.array(containers, copy=False, dtype=float)
+    rect_sizes = numpy.array(rects, copy=False, dtype=float)
     rect_locs = numpy.zeros_like(rect_sizes)
     rejected_inds = set()
 
@@ -227,7 +227,7 @@ def pack_patterns(
         MasqueError if `allow_rejects` is `True` but some `rects` could not be placed.
     """
 
-    half_spacing = numpy.asarray(spacing, dtype=float) / 2
+    half_spacing = numpy.array(spacing, copy=False, dtype=float) / 2
 
     bounds = [library[pp].get_bounds() for pp in patterns]
     sizes = [bb[1] - bb[0] + spacing if bb is not None else spacing for bb in bounds]
diff --git a/masque/utils/vertices.py b/masque/utils/vertices.py
index 23fb601..0c5f03b 100644
--- a/masque/utils/vertices.py
+++ b/masque/utils/vertices.py
@@ -15,9 +15,9 @@ def remove_duplicate_vertices(vertices: ArrayLike, closed_path: bool = True) ->
             (i.e. the last vertex will be removed if it is the same as the first)
 
     Returns:
-        `vertices` with no consecutive duplicates. This may be a view into the original array.
+        `vertices` with no consecutive duplicates.
     """
-    vertices = numpy.asarray(vertices)
+    vertices = numpy.array(vertices)
     duplicates = (vertices == numpy.roll(vertices, 1, axis=0)).all(axis=1)
     if not closed_path:
         duplicates[0] = False
@@ -35,7 +35,7 @@ def remove_colinear_vertices(vertices: ArrayLike, closed_path: bool = True) -> N
            closed path. If `False`, the path is assumed to be open. Default `True`.
 
     Returns:
-        `vertices` with colinear (superflous) vertices removed. May be a view into the original array.
+        `vertices` with colinear (superflous) vertices removed.
     """
     vertices = remove_duplicate_vertices(vertices)
 
@@ -73,8 +73,8 @@ def poly_contains_points(
     Returns:
         ndarray of booleans, [point0_is_in_shape, point1_is_in_shape, ...]
     """
-    points = numpy.asarray(points, dtype=float)
-    vertices = numpy.asarray(vertices, dtype=float)
+    points = numpy.array(points, copy=False)
+    vertices = numpy.array(vertices, copy=False)
 
     if points.size == 0:
         return numpy.zeros(0, dtype=numpy.int8)