diff --git a/docs/changelog/new-instance-variable-components.md b/docs/changelog/new-instance-variable-components.md
new file mode 100644
index 000000000..90c43fd75
--- /dev/null
+++ b/docs/changelog/new-instance-variable-components.md
@@ -0,0 +1,16 @@
+# Enable new instances of unknown arrays with dynamic sizes
+
+`UnknownArrayHandle` allows you to create a new instance of a compatible
+array so that when receiving an array of unknown type, a place to put the
+output can be created. However, these methods only worked if the number of
+components in each value could be determined statically at compile time.
+
+However, there are some special `ArrayHandle`s that can define the number
+of components at runtime. In this case, the `ArrayHandle` would throw an
+exception if `NewInstanceBasic` or `NewInstanceFloatBasic` was called.
+
+Although rare, this condition could happen when, for example, an array was
+extracted from an `UnknownArrayHandle` with `ExtractArrayFromComponents` or
+with `CastAndCallWithExtractedArray` and then the resulting array was
+passed to a function with arrays passed with `UnknownArrayHandle` such as
+`ArrayCopy`.
diff --git a/vtkm/cont/UnknownArrayHandle.cxx b/vtkm/cont/UnknownArrayHandle.cxx
index 21037bc99..80644f480 100644
--- a/vtkm/cont/UnknownArrayHandle.cxx
+++ b/vtkm/cont/UnknownArrayHandle.cxx
@@ -219,7 +219,7 @@ VTKM_CONT UnknownArrayHandle UnknownArrayHandle::NewInstanceBasic() const
   }
   if (this->Container)
   {
-    newArray.Container = this->Container->NewInstanceBasic();
+    newArray.Container = this->Container->NewInstanceBasic(this->Container->ArrayHandlePointer);
   }
   return newArray;
 }
@@ -237,7 +237,8 @@ VTKM_CONT UnknownArrayHandle UnknownArrayHandle::NewInstanceFloatBasic() const
   UnknownArrayHandle newArray;
   if (this->Container)
   {
-    newArray.Container = this->Container->NewInstanceFloatBasic();
+    newArray.Container =
+      this->Container->NewInstanceFloatBasic(this->Container->ArrayHandlePointer);
   }
   return newArray;
 }
diff --git a/vtkm/cont/UnknownArrayHandle.h b/vtkm/cont/UnknownArrayHandle.h
index 4370294c4..534e1cb06 100644
--- a/vtkm/cont/UnknownArrayHandle.h
+++ b/vtkm/cont/UnknownArrayHandle.h
@@ -231,7 +231,7 @@ struct VTKM_CONT_EXPORT UnknownAHContainer
   using NewInstanceType = void*();
   NewInstanceType* NewInstance;
 
-  using NewInstanceBasicType = std::shared_ptr<UnknownAHContainer>();
+  using NewInstanceBasicType = std::shared_ptr<UnknownAHContainer>(void*);
   NewInstanceBasicType* NewInstanceBasic;
   NewInstanceBasicType* NewInstanceFloatBasic;
 
@@ -307,39 +307,56 @@ private:
   explicit UnknownAHContainer(const vtkm::cont::ArrayHandle<T, S>& array);
 };
 
-template <typename T>
-std::shared_ptr<UnknownAHContainer> UnknownAHNewInstanceBasic(vtkm::VecTraitsTagSizeStatic)
+template <typename T, typename S>
+std::shared_ptr<UnknownAHContainer> UnknownAHNewInstanceBasic(void*, vtkm::VecTraitsTagSizeStatic)
 {
   return UnknownAHContainer::Make(vtkm::cont::ArrayHandleBasic<T>{});
 }
-template <typename T>
-std::shared_ptr<UnknownAHContainer> UnknownAHNewInstanceBasic(vtkm::VecTraitsTagSizeVariable)
+template <typename T, typename S>
+std::shared_ptr<UnknownAHContainer> UnknownAHNewInstanceBasic(void* mem,
+                                                              vtkm::VecTraitsTagSizeVariable)
 {
-  throw vtkm::cont::ErrorBadType("Cannot create a basic array container from with ValueType of " +
-                                 vtkm::cont::TypeToString<T>());
+  vtkm::IdComponent numComponents = UnknownAHNumberOfComponentsFlat<T, S>(mem);
+  if (numComponents < 1)
+  {
+    // Array can have an inconsistent number of components. Cannot be represented by basic array.
+    throw vtkm::cont::ErrorBadType("Cannot create a basic array from array with ValueType of " +
+                                   vtkm::cont::TypeToString<T>());
+  }
+  using ComponentType = typename vtkm::VecTraits<T>::BaseComponentType;
+  return UnknownAHContainer::Make(vtkm::cont::ArrayHandleRuntimeVec<ComponentType>(numComponents));
 }
-template <typename T>
-std::shared_ptr<UnknownAHContainer> UnknownAHNewInstanceBasic()
+template <typename T, typename S>
+std::shared_ptr<UnknownAHContainer> UnknownAHNewInstanceBasic(void* mem)
 {
-  return UnknownAHNewInstanceBasic<T>(typename vtkm::VecTraits<T>::IsSizeStatic{});
+  return UnknownAHNewInstanceBasic<T, S>(mem, typename vtkm::VecTraits<T>::IsSizeStatic{});
 }
 
-template <typename T>
-std::shared_ptr<UnknownAHContainer> UnknownAHNewInstanceFloatBasic(vtkm::VecTraitsTagSizeStatic)
+template <typename T, typename S>
+std::shared_ptr<UnknownAHContainer> UnknownAHNewInstanceFloatBasic(void*,
+                                                                   vtkm::VecTraitsTagSizeStatic)
 {
   using FloatT = typename vtkm::VecTraits<T>::template ReplaceBaseComponentType<vtkm::FloatDefault>;
   return UnknownAHContainer::Make(vtkm::cont::ArrayHandleBasic<FloatT>{});
 }
-template <typename T>
-std::shared_ptr<UnknownAHContainer> UnknownAHNewInstanceFloatBasic(vtkm::VecTraitsTagSizeVariable)
+template <typename T, typename S>
+std::shared_ptr<UnknownAHContainer> UnknownAHNewInstanceFloatBasic(void* mem,
+                                                                   vtkm::VecTraitsTagSizeVariable)
 {
-  throw vtkm::cont::ErrorBadType("Cannot create a basic array container from with ValueType of " +
-                                 vtkm::cont::TypeToString<T>());
+  vtkm::IdComponent numComponents = UnknownAHNumberOfComponentsFlat<T, S>(mem);
+  if (numComponents < 1)
+  {
+    // Array can have an inconsistent number of components. Cannot be represented by basic array.
+    throw vtkm::cont::ErrorBadType("Cannot create a basic array from array with ValueType of " +
+                                   vtkm::cont::TypeToString<T>());
+  }
+  return UnknownAHContainer::Make(
+    vtkm::cont::ArrayHandleRuntimeVec<vtkm::FloatDefault>(numComponents));
 }
-template <typename T>
-std::shared_ptr<UnknownAHContainer> UnknownAHNewInstanceFloatBasic()
+template <typename T, typename S>
+std::shared_ptr<UnknownAHContainer> UnknownAHNewInstanceFloatBasic(void* mem)
 {
-  return UnknownAHNewInstanceFloatBasic<T>(typename vtkm::VecTraits<T>::IsSizeStatic{});
+  return UnknownAHNewInstanceFloatBasic<T, S>(mem, typename vtkm::VecTraits<T>::IsSizeStatic{});
 }
 
 template <typename T, typename S>
@@ -352,8 +369,8 @@ inline UnknownAHContainer::UnknownAHContainer(const vtkm::cont::ArrayHandle<T, S
   , DeleteFunction(detail::UnknownAHDelete<T, S>)
   , Buffers(detail::UnknownAHBuffers<T, S>)
   , NewInstance(detail::UnknownAHNewInstance<T, S>)
-  , NewInstanceBasic(detail::UnknownAHNewInstanceBasic<T>)
-  , NewInstanceFloatBasic(detail::UnknownAHNewInstanceFloatBasic<T>)
+  , NewInstanceBasic(detail::UnknownAHNewInstanceBasic<T, S>)
+  , NewInstanceFloatBasic(detail::UnknownAHNewInstanceFloatBasic<T, S>)
   , NumberOfValues(detail::UnknownAHNumberOfValues<T, S>)
   , NumberOfComponents(detail::UnknownAHNumberOfComponents<T, S>)
   , NumberOfComponentsFlat(detail::UnknownAHNumberOfComponentsFlat<T, S>)
diff --git a/vtkm/cont/testing/UnitTestArrayCopy.cxx b/vtkm/cont/testing/UnitTestArrayCopy.cxx
index 9ca8d59dc..2ed5e08e6 100644
--- a/vtkm/cont/testing/UnitTestArrayCopy.cxx
+++ b/vtkm/cont/testing/UnitTestArrayCopy.cxx
@@ -254,6 +254,44 @@ void TryCopy()
                  ARRAY_SIZE));
   }
 
+  {
+    std::cout << "runtime vec size -> runtime vec size (different type)" << std::endl;
+    using ComponentType = typename VTraits::BaseComponentType;
+    using SourceType = typename VTraits::template ReplaceComponentType<vtkm::UInt8>;
+    vtkm::cont::ArrayHandle<SourceType> staticVecArray = MakeInputArray<SourceType>();
+    vtkm::cont::ArrayHandleRuntimeVec<vtkm::UInt8> input =
+      vtkm::cont::make_ArrayHandleRuntimeVec(staticVecArray);
+    vtkm::cont::ArrayHandleRuntimeVec<ComponentType> output(input.GetNumberOfComponents());
+    vtkm::cont::ArrayCopy(input, output);
+    // Convert the arrays back to static vec sizes for comparison, because TestValues
+    // uses a device array copy that may not work on runtime vec sizes.
+    TestValues(staticVecArray,
+               output.template AsArrayHandleBasic<vtkm::cont::ArrayHandle<ValueType>>());
+  }
+
+  {
+    std::cout << "basic -> recombined vec" << std::endl;
+    using ComponentType = typename VTraits::BaseComponentType;
+    vtkm::cont::ArrayHandle<ValueType> input = MakeInputArray<ValueType>();
+    vtkm::cont::ArrayHandle<ValueType> output;
+    auto recombinedVec =
+      vtkm::cont::UnknownArrayHandle{ output }.ExtractArrayFromComponents<ComponentType>();
+    vtkm::cont::ArrayCopy(input, recombinedVec);
+    TestValues(input, output);
+  }
+
+  {
+    std::cout << "basic -> recombined vec (different type)" << std::endl;
+    using SourceType = typename VTraits::template ReplaceComponentType<vtkm::Id>;
+    using ComponentType = typename VTraits::BaseComponentType;
+    vtkm::cont::ArrayHandle<SourceType> input = MakeInputArray<SourceType>();
+    vtkm::cont::ArrayHandle<ValueType> output;
+    auto recombinedVec =
+      vtkm::cont::UnknownArrayHandle{ output }.ExtractArrayFromComponents<ComponentType>();
+    vtkm::cont::ArrayCopy(input, recombinedVec);
+    TestValues(input, output);
+  }
+
   // Test the copy methods in UnknownArrayHandle. Although this would be appropriate in
   // UnitTestUnknownArrayHandle, it is easier to test copies here.
   {
diff --git a/vtkm/cont/testing/UnitTestUnknownArrayHandle.cxx b/vtkm/cont/testing/UnitTestUnknownArrayHandle.cxx
index 6b9f8045c..fa66c6f2a 100644
--- a/vtkm/cont/testing/UnitTestUnknownArrayHandle.cxx
+++ b/vtkm/cont/testing/UnitTestUnknownArrayHandle.cxx
@@ -479,6 +479,18 @@ struct CheckExtractedArray
       auto extractedData = extractedPortal.Get(valueIndex);
       VTKM_TEST_ASSERT(test_equal(originalData, extractedData));
     }
+
+    // Make sure an extracted array stuffed back into an UnknownArrayHandle works.
+    // This can happen when working with an extracted array that is passed to functions
+    // that are implemented with UnknownArrayHandle.
+    vtkm::cont::UnknownArrayHandle unknownArray{ extractedArray };
+
+    using ComponentType =
+      typename vtkm::VecTraits<typename ExtractedArray::ValueType>::BaseComponentType;
+    vtkm::cont::UnknownArrayHandle newBasic = unknownArray.NewInstanceBasic();
+    newBasic.AsArrayHandle<vtkm::cont::ArrayHandleRuntimeVec<ComponentType>>();
+    vtkm::cont::UnknownArrayHandle newFloat = unknownArray.NewInstanceFloatBasic();
+    newFloat.AsArrayHandle<vtkm::cont::ArrayHandleRuntimeVec<vtkm::FloatDefault>>();
   }
 };