diff --git a/src/main.cpp b/src/main.cpp
index 309e34d..edd0eb2 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,5 +1,10 @@
 #include <pybind11/pybind11.h>
+#include <pybind11/numpy.h> // for py::array_t
 #include "barry.hpp"
+#include "models/defm.hpp"
+#include <vector>
+
+namespace py = pybind11;
 
 #define STRINGIFY(x) #x
 #define MACRO_STRINGIFY(x) STRINGIFY(x)
@@ -8,7 +13,37 @@ int add(int i, int j) {
     return i + j;
 }
 
-namespace py = pybind11;
+
+std::shared_ptr< defm::DEFM > new_defm(
+    py::array_t< int > id,
+    py::array_t< int > y,
+    py::array_t< double > x
+    ) {
+
+    // std::vector<int> id = {1, 2, 3, 4, 5};
+    // std::vector<int> y = {1, 2, 3, 4, 5};
+    // std::vector<double> x = {1.0, 2.0, 3.0, 4.0, 5.0};
+
+    int n_id = id.size();
+    int n_y = y.size();
+    int n_x = x.size();
+
+    std::shared_ptr< defm::DEFM > object(new defm::DEFM(
+        id.mutable_data(0u),
+        y.mutable_data(0u),
+        x.mutable_data(0u),
+        static_cast< size_t >(n_id),
+        static_cast< size_t >(n_y),
+        static_cast< size_t >(n_x),
+        false,
+        false
+    ));
+
+    return object;
+}
+
+
+
 
 PYBIND11_MODULE(_core, m) {
     m.doc() = R"pbdoc(
@@ -30,12 +65,29 @@ PYBIND11_MODULE(_core, m) {
         Some other explanation about the add function.
     )pbdoc");
 
+    // Example with lambda function
     m.def("subtract", [](int i, int j) { return i - j; }, R"pbdoc(
         Subtract two numbers
 
         Some other explanation about the subtract function.
     )pbdoc");
 
+    // Only this is necesary to expose the class
+    py::class_<defm::DEFM, std::shared_ptr<defm::DEFM>>(m, "DEFM")
+        // .def(py::init<>())
+        .def("print", &defm::DEFM::print, R"pbdoc(
+            Print the object
+
+            Some other explanation about the print function.)
+        )pbdoc");
+
+    // Example with shared_ptr
+    m.def("new_defm", &new_defm, R"pbdoc(
+        Create a new DEFM object
+
+        Some other explanation about the new_defm function.
+    )pbdoc");
+
 #ifdef VERSION_INFO
     m.attr("__version__") = MACRO_STRINGIFY(VERSION_INFO);
 #else
diff --git a/src/scikit_build_example/__init__.py b/src/scikit_build_example/__init__.py
index 15188e5..a81b80b 100644
--- a/src/scikit_build_example/__init__.py
+++ b/src/scikit_build_example/__init__.py
@@ -1,5 +1,5 @@
 from __future__ import annotations
 
-from ._core import __doc__, __version__, add, subtract
+from ._core import __doc__, __version__, add, subtract, new_defm
 
-__all__ = ["__doc__", "__version__", "add", "subtract"]
+__all__ = ["__doc__", "__version__", "add", "subtract", "new_defm"]
diff --git a/tests/test_basic.py b/tests/test_basic.py
index 93da71b..7ce9a1a 100644
--- a/tests/test_basic.py
+++ b/tests/test_basic.py
@@ -1,6 +1,13 @@
 from __future__ import annotations
 
 import scikit_build_example as m
+import numpy as np
+
+y = np.array([1, 2, 3])
+x = np.array([1, 2, 3])
+id = np.array([1, 2, 3])
+
+m.new_defm(y, x, id)
 
 
 def test_version():