diff --git a/include/core/invm_handler.h b/include/core/invm_handler.h
new file mode 100644
index 000000000..5143b5928
--- /dev/null
+++ b/include/core/invm_handler.h
@@ -0,0 +1,142 @@
+#ifndef invm_handler_h
+#define invm_handler_h
+
+#include <deal.II/lac/la_parallel_vector.h>
+
+#include <core/exceptions.h>
+#include <core/user_inputs/user_input_parameters.h>
+#include <core/variable_attributes.h>
+
+/**
+ * \brief This class handles the computation and access of the inverted mass matrix for
+ * explicit solves.
+ */
+template <int dim, int degree>
+class invmHandler
+{
+public:
+  /**
+   * \brief Constructor.
+   */
+  invmHandler(const AttributesList &_variable_attributes);
+
+  /**
+   * \brief Destructor.
+   */
+  ~invmHandler();
+
+  /**
+   * \brief Compute the mass matrix for scalar/vector fields.
+   */
+  void
+  compute_invm();
+
+  /**
+   * \brief Recompute the mass matrix for scalar/vector fields. This just points to
+   * compute_invm() and is used for style.
+   */
+  void
+  recompute_invm();
+
+  /**
+   * \brief  Getter function for the mass matrix for the given field index (constant
+   * reference).
+   */
+  const dealii::LinearAlgebra::distributed::Vector<double> &
+  get_invm(const uint &index);
+
+private:
+  /**
+   * \brief Variable attributes. This is used to determine the proper return type for the
+   * invm when given a field index.
+   */
+  const AttributesList &variable_attributes;
+
+  /**
+   * \brief Inverse of the mass matrix for scalar fields.
+   */
+  dealii::LinearAlgebra::distributed::Vector<double> invm_scalar;
+
+  /**
+   * \brief Inverse of the mass matrix for vector fields.
+   */
+  dealii::LinearAlgebra::distributed::Vector<double> invm_vector;
+
+  /**
+   * \brief Whether a scalar invm is needed.
+   */
+  bool scalar_needed = false;
+
+  /**
+   * \brief Whether a vector invm is needed.
+   */
+  bool vector_needed = false;
+};
+
+template <int dim, int degree>
+invmHandler<dim, degree>::invmHandler(const AttributesList &_variable_attributes)
+  : variable_attributes(_variable_attributes)
+{
+  for (const auto &[index, variable] : variable_attributes)
+    {
+      if (variable.field_type == fieldType::SCALAR)
+        {
+          scalar_needed = true;
+        }
+      if (variable.field_type == fieldType::VECTOR)
+        {
+          vector_needed = true;
+        }
+    }
+}
+
+template <int dim, int degree>
+inline void
+invmHandler<dim, degree>::compute_invm()
+{}
+
+template <int dim, int degree>
+inline void
+invmHandler<dim, degree>::recompute_invm()
+{
+  this->compute_invm();
+}
+
+template <int dim, int degree>
+inline const dealii::LinearAlgebra::distributed::Vector<double> &
+invmHandler<dim, degree>::get_invm(const uint &index)
+{
+  Assert(variable_attributes.at(index) != variable_attributes.end(),
+         dealii::ExcMessage(
+           "Invalid index. The provided index does not have an entry in the variable "
+           "attributes that were provided to the constructor."));
+
+  if (variable_attributes.at(index).field_type == fieldType::SCALAR)
+    {
+      Assert(scalar_needed,
+             dealii::ExcMessage(
+               "The invm for scalar fields is marked as not needed. Make sure the "
+               "variable attributes correspond with the provided index."));
+      Assert(invm_scalar.size() == 0,
+             dealii::ExcMessage("The scalar invm has size 0. Please make sure to call "
+                                "compute_invm() prior to calling the getter function."));
+
+      return invm_scalar;
+    }
+  else if (variable_attributes.at(index).field_type == fieldType::VECTOR)
+    {
+      Assert(vector_needed,
+             dealii::ExcMessage(
+               "The invm for vector fields is marked as not needed. Make sure the "
+               "variable attributes correspond with the provided index."));
+      Assert(invm_vector.size() == 0,
+             dealii::ExcMessage("The vector invm has size 0. Please make sure to call "
+                                "compute_invm() prior to calling the getter function."));
+
+      return invm_vector;
+    }
+
+  Assert(false, dealii::ExcMessage("Invalid field type."));
+}
+
+#endif
\ No newline at end of file
diff --git a/include/core/solvers/explicit_constant_solver.h b/include/core/solvers/explicit_constant_solver.h
new file mode 100644
index 000000000..7bb65815c
--- /dev/null
+++ b/include/core/solvers/explicit_constant_solver.h
@@ -0,0 +1,10 @@
+#ifndef explicit_constant_solver_h
+#define explicit_constant_solver_h
+
+/**
+ * \brief This class handles the explicit solves of all constant fields
+ */
+class explicitConstantSolver
+{};
+
+#endif
\ No newline at end of file
diff --git a/include/core/solvers/explicit_postprocess_solver.h b/include/core/solvers/explicit_postprocess_solver.h
new file mode 100644
index 000000000..1c110244a
--- /dev/null
+++ b/include/core/solvers/explicit_postprocess_solver.h
@@ -0,0 +1,10 @@
+#ifndef explicit_postprocess_solver_h
+#define explicit_postprocess_solver_h
+
+/**
+ * \brief This class handles the explicit solves of all postprocessed fields
+ */
+class explicitPostprocessSolver
+{};
+
+#endif
\ No newline at end of file
diff --git a/include/core/solvers/explicit_solver.h b/include/core/solvers/explicit_solver.h
new file mode 100644
index 000000000..73d3da2ff
--- /dev/null
+++ b/include/core/solvers/explicit_solver.h
@@ -0,0 +1,39 @@
+#ifndef explicit_solver_h
+#define explicit_solver_h
+
+/**
+ * \brief This class handles the explicit solves of all explicit fields
+ */
+class explicitSolver
+{
+public:
+  /**
+   * \brief Constructor.
+   */
+  explicitSolver();
+
+  /**
+   * \brief Destructor.
+   */
+  ~explicitSolver();
+
+  /**
+   * \brief Initialize system.
+   */
+  void
+  init_system();
+
+  /**
+   * \brief Reinitialize system.
+   */
+  void
+  reinit_system();
+
+  /**
+   * \brief Solve a single update step.
+   */
+  void
+  solve();
+};
+
+#endif
\ No newline at end of file
diff --git a/include/core/solvers/nonexplicit_auxiliary_solver.h b/include/core/solvers/nonexplicit_auxiliary_solver.h
new file mode 100644
index 000000000..24fbe61c6
--- /dev/null
+++ b/include/core/solvers/nonexplicit_auxiliary_solver.h
@@ -0,0 +1,10 @@
+#ifndef nonexplicit_auxiliary_solver_h
+#define nonexplicit_auxiliary_solver_h
+
+/**
+ * \brief This class handles the explicit solves of a single nonexplicit field
+ */
+class nonexplicitAuxiliarySolves
+{};
+
+#endif
\ No newline at end of file
diff --git a/include/core/solvers/nonexplicit_co_nonlinear_solver.h b/include/core/solvers/nonexplicit_co_nonlinear_solver.h
new file mode 100644
index 000000000..dae004fca
--- /dev/null
+++ b/include/core/solvers/nonexplicit_co_nonlinear_solver.h
@@ -0,0 +1,10 @@
+#ifndef nonexplicit_co_nonlinear_solver_h
+#define nonexplicit_co_nonlinear_solver_h
+
+/**
+ * \brief This class handles the nonlinear solves of a several nonexplicit fields
+ */
+class nonexplicitCoNonlinearSolver
+{};
+
+#endif
\ No newline at end of file
diff --git a/include/core/solvers/nonexplicit_linear_solver.h b/include/core/solvers/nonexplicit_linear_solver.h
new file mode 100644
index 000000000..3353f1bb8
--- /dev/null
+++ b/include/core/solvers/nonexplicit_linear_solver.h
@@ -0,0 +1,10 @@
+#ifndef nonexplicit_linear_solver_h
+#define nonexplicit_linear_solver_h
+
+/**
+ * \brief This class handles the linear solves of a single nonexplicit field
+ */
+class nonexplicitLinearSolver
+{};
+
+#endif
\ No newline at end of file
diff --git a/include/core/solvers/nonexplicit_self_nonlinear_solver.h b/include/core/solvers/nonexplicit_self_nonlinear_solver.h
new file mode 100644
index 000000000..23f42b9b6
--- /dev/null
+++ b/include/core/solvers/nonexplicit_self_nonlinear_solver.h
@@ -0,0 +1,10 @@
+#ifndef nonexplicit_self_nonlinear_solver_h
+#define nonexplicit_self_nonlinear_solver_h
+
+/**
+ * \brief This class handles the self-nonlinear solves of a single nonexplicit field
+ */
+class nonexplicitSelfNonlinearSolver
+{};
+
+#endif
\ No newline at end of file