diff --git a/.flake8 b/.flake8
new file mode 100644
index 0000000..8dd399a
--- /dev/null
+++ b/.flake8
@@ -0,0 +1,3 @@
+[flake8]
+max-line-length = 88
+extend-ignore = E203
diff --git a/mcl/bindings.py b/mcl/bindings.py
new file mode 100644
index 0000000..c997ca3
--- /dev/null
+++ b/mcl/bindings.py
@@ -0,0 +1,51 @@
+import ctypes
+import inspect
+
+from . import hook, utils
+
+MCL_NAME = "__mcl_name__"
+
+
+def is_mcl_method(obj):
+    return inspect.ismethod(obj) and hasattr(obj, MCL_NAME)
+
+
+def method_binding(method_name=None):
+    def decorator(method_obj):
+        setattr(method_obj, MCL_NAME, method_name or method_obj.__name__)
+        return method_obj
+
+    return decorator
+
+
+def _build_mcl_ctypes_binding(method_obj, mcl_method_name, klass_instance):
+    wrapper = utils.wrap_function(
+        hook.mclbls12_384,
+        mcl_method_name,
+        [
+            ctypes.POINTER(klass_instance),
+            ctypes.c_char_p,
+            ctypes.c_size_t,
+            ctypes.c_int64,
+        ],
+    )
+    return wrapper
+
+
+def class_binding():
+    def decorator(klass_instance):
+        method_name_obj_pairs = inspect.getmembers(
+            klass_instance, predicate=is_mcl_method
+        )
+
+        for method_name, method_obj in method_name_obj_pairs:
+            mcl_method_name = getattr(method_obj, MCL_NAME)
+            setattr(
+                klass_instance,
+                method_name,
+                _build_mcl_ctypes_binding(method_obj, mcl_method_name, klass_instance),
+            )
+
+        return klass_instance
+
+    return decorator
diff --git a/mcl/builder.py b/mcl/builder.py
index 7c0cb57..6203111 100644
--- a/mcl/builder.py
+++ b/mcl/builder.py
@@ -2,13 +2,12 @@
 import dataclasses
 import inspect
 
-from . import hook
-from . import utils
+from . import hook, utils
 
 BUFFER_SIZE = 2048
 
 
-def tryGetBuilderMethodFromGlobals(method_name: str) -> callable:
+def tryGetBuilderMethodFromGlobals(method_name: str):
     return globals().get("build" + method_name[0].upper() + method_name[1:])
 
 
@@ -51,7 +50,12 @@ def buildSetStr(cls):
     wrapper = utils.wrap_function(
         hook.mclbls12_384,
         f"mclBn{cls.__name__}_setStr",
-        [ctypes.POINTER(cls), ctypes.c_char_p, ctypes.c_size_t, ctypes.c_int64],
+        [
+            ctypes.POINTER(cls),
+            ctypes.c_char_p,
+            ctypes.c_size_t,
+            ctypes.c_int64,
+        ],
     )
 
     def setStr(self, value, mode=10):
@@ -75,7 +79,9 @@ def setInt(self, value):
 
 def buildSetByCSPRNG(cls):
     wrapper = utils.wrap_function(
-        hook.mclbls12_384, f"mclBn{cls.__name__}_setByCSPRNG", [ctypes.POINTER(cls)],
+        hook.mclbls12_384,
+        f"mclBn{cls.__name__}_setByCSPRNG",
+        [ctypes.POINTER(cls)],
     )
 
     def setByCSPRNG(self):
@@ -120,7 +126,9 @@ def isEqual(self, other):
 
 def buildIsOne(cls):
     wrapper = utils.wrap_function(
-        hook.mclbls12_384, f"mclBn{cls.__name__}_isOne", [ctypes.POINTER(cls)],
+        hook.mclbls12_384,
+        f"mclBn{cls.__name__}_isOne",
+        [ctypes.POINTER(cls)],
     )
 
     def isOne(self, other):
@@ -248,7 +256,11 @@ def buildPairing(cls, left_group, right_group):
     wrapper = utils.wrap_function(
         hook.mclbls12_384,
         f"mclBn_pairing",
-        (ctypes.POINTER(cls), ctypes.POINTER(left_group), ctypes.POINTER(right_group)),
+        (
+            ctypes.POINTER(cls),
+            ctypes.POINTER(left_group),
+            ctypes.POINTER(right_group),
+        ),
     )
 
     @staticmethod
diff --git a/mcl/structures/Fp.py b/mcl/structures/Fp.py
index 9bb65f3..524cb3c 100644
--- a/mcl/structures/Fp.py
+++ b/mcl/structures/Fp.py
@@ -1,7 +1,6 @@
 import ctypes
 
-from .. import builder
-from .. import consts
+from .. import builder, consts
 
 
 @builder.provide_methods(
@@ -23,3 +22,8 @@
 )
 class Fp(ctypes.Structure):
     _fields_ = [("v", ctypes.c_ulonglong * consts.FP_SIZE)]
+
+    def __repr__(self):
+        import pdb
+
+        pdb.set_trace()
diff --git a/mcl/structures/Fr.py b/mcl/structures/Fr.py
index 95618ff..f0a4063 100644
--- a/mcl/structures/Fr.py
+++ b/mcl/structures/Fr.py
@@ -1,25 +1,94 @@
 import ctypes
 
-from .. import builder
-from .. import consts
-
-
-@builder.provide_methods(
-    builder.method("__add__").using(builder.buildThreeOp).with_args("add"),
-    builder.method("__eq__").using(builder.buildIsEqual),
-    builder.method("__invert__").using(builder.buildTwoOp).with_args("inv"),
-    builder.method("__mul__").using(builder.buildThreeOp).with_args("mul"),
-    builder.method("__neg__").using(builder.buildTwoOp).with_args("neg"),
-    builder.method("__sub__").using(builder.buildThreeOp).with_args("sub"),
-    builder.method("__truediv__").using(builder.buildThreeOp).with_args("div"),
-    builder.method("deserialize"),
-    builder.method("getStr"),
-    builder.method("isOne"),
-    builder.method("isZero"),
-    builder.method("serialize"),
-    builder.method("setByCSPRNG"),
-    builder.method("setInt"),
-    builder.method("setStr"),
-)
+from .. import hook
+
+mclbn384_256 = hook.mclbls12_384
+
+
 class Fr(ctypes.Structure):
-    _fields_ = [("v", ctypes.c_ulonglong * consts.FR_SIZE)]
+    _fields_ = [("v", ctypes.c_ulonglong * 6)]
+
+    def __init__(self, value=None):
+        if value is None:
+            return
+
+        if isinstance(value, str):
+            self.setStr(value)
+        elif isinstance(value, int):
+            self.setInt(value)
+
+    def setInt(self, v):
+        mclbn384_256.mclBnFr_setInt(ctypes.byref(self.v), v)
+
+    def setStr(self, value: str):
+        value = value if isinstance(value, bytes) else value.encode()
+        error = mclbn384_256.mclBnFr_setStr(
+            ctypes.byref(self.v), ctypes.c_char_p(value), len(value), 10
+        )
+        if error:
+            raise RuntimeError("mclBnFr_setStr failed")
+
+    def getStr(self):
+        svLen = 2048
+        sv = ctypes.create_string_buffer(b"\0" * svLen)
+        mclbn384_256.mclBnFr_getStr(sv, svLen, ctypes.byref(self.v), 10)
+        return sv.value.decode()
+
+    def isZero(self):
+        return mclbn384_256.mclBnFr_isZero(ctypes.byref(self.v)) != 0
+
+    def isOne(self):
+        return mclbn384_256.mclBnFr_isOne(ctypes.byref(self.v)) != 0
+
+    def setByCSPRNG(self):
+        return mclbn384_256.mclBnFr_setByCSPRNG(ctypes.byref(self.v))
+
+    @classmethod
+    def random(cls):
+        value = cls()
+        value.setByCSPRNG()
+        return value
+
+    def __eq__(self, rhs):
+        return (
+            mclbn384_256.mclBnFr_isEqual(ctypes.byref(self.v), ctypes.byref(rhs.v)) != 0
+        )
+
+    def __ne__(self, rhs):
+        return not (self == rhs)
+
+    def __add__(self, rhs):
+        ret = Fr()
+        mclbn384_256.mclBnFr_add(
+            ctypes.byref(ret.v), ctypes.byref(self.v), ctypes.byref(rhs.v)
+        )
+        return ret
+
+    def __sub__(self, rhs):
+        ret = Fr()
+        mclbn384_256.mclBnFr_sub(
+            ctypes.byref(ret.v), ctypes.byref(self.v), ctypes.byref(rhs.v)
+        )
+        return ret
+
+    def __mul__(self, rhs):
+        ret = Fr()
+        mclbn384_256.mclBnFr_mul(
+            ctypes.byref(ret.v), ctypes.byref(self.v), ctypes.byref(rhs.v)
+        )
+        return ret
+
+    def __div__(self, rhs):
+        ret = Fr()
+        mclbn384_256.mclBnFr_div(
+            ctypes.byref(ret.v), ctypes.byref(self.v), ctypes.byref(rhs.v)
+        )
+        return ret
+
+    def __invert__(self):
+        ret = Fr()
+        mclbn384_256.mclBnFr_neg(ctypes.byref(ret.v), ctypes.byref(self.v))
+        return ret
+
+    def __repr__(self):
+        return f"Fr({self.getStr()})"
diff --git a/mcl/structures/G1.py b/mcl/structures/G1.py
index 69152fe..e260e2c 100644
--- a/mcl/structures/G1.py
+++ b/mcl/structures/G1.py
@@ -1,8 +1,7 @@
-import types
 import ctypes
+import types
 
-from .. import utils
-from .. import builder
+from .. import builder, utils
 from .Fp import Fp
 from .Fr import Fr
 
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..6d6e6fb
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,2 @@
+[tool.black]
+exclude = 'venv'
diff --git a/tests/test_fr.py b/tests/test_fr.py
index c3d9e81..641868e 100644
--- a/tests/test_fr.py
+++ b/tests/test_fr.py
@@ -3,29 +3,58 @@
 from mcl import Fr
 
 
+def createRandomFr() -> Fr:
+    fr = Fr()
+    fr.setByCSPRNG()
+    return fr
+
+
 class FrTests(unittest.TestCase):
+
+    def testAdd(self):
+        self.assertEqual(Fr(30), Fr(10) + Fr(20))
+
+    def testEquals(self):
+        self.assertEqual(Fr(20), Fr(20))
+
+    def testInvert(self):
+        self.assertEqual(Fr(10), ~~Fr(10))
+
+    def testMul(self):
+        self.assertEqual(Fr(8), Fr(4) * Fr(2))
+
     def testInitFr(self):
         self.assertIsNotNone(Fr())
 
     def testSetStr(self):
-        Fr().setStr(b"12345678901234567")
+        # Arrange.
+        expected = "1234567"
+        fr = Fr()
+
+        # Act.
+        fr.setStr("1234567")
+
+        # Assert.
+        self.assertEqual(expected, fr.getStr())
 
     def testIsEqual(self):
-        l = Fr()
-        l.setByCSPRNG()
-        self.assertTrue(l == l)
+        # Arrange.
+        fr = createRandomFr()
+
+        fr2 = Fr()
+        fr2.setStr(fr.getStr())
+
+        self.assertEqual(fr, fr2)
 
     def testSetInt(self):
         Fr().setInt(1)
 
-    def testMul(self):
-        Fr() * Fr()
-
     def testGetStr(self):
         fr = Fr()
-        fr.setStr(b"255")
+        fr.setStr("255")
         s = fr.getStr()
-        self.assertEqual(b"255", s)
+        self.assertEqual("255", s)
 
     def testByCSPRNG(self):
         Fr().setByCSPRNG()
+
diff --git a/tests/test_g1.py b/tests/test_g1.py
index 9faa9f4..df76bc4 100644
--- a/tests/test_g1.py
+++ b/tests/test_g1.py
@@ -3,7 +3,7 @@
 from mcl import G1
 from mcl import Fr
 
-from . import test_data
+from tests import test_data
 
 
 class G1Tests(unittest.TestCase):
diff --git a/tests/test_g2.py b/tests/test_g2.py
index 0045546..97a7827 100644
--- a/tests/test_g2.py
+++ b/tests/test_g2.py
@@ -3,7 +3,7 @@
 from mcl import G2
 from mcl import Fr
 
-from . import test_data
+from tests import test_data
 
 
 class G2Tests(unittest.TestCase):
diff --git a/tests/test_gt.py b/tests/test_gt.py
index 2b527cf..8cae55d 100644
--- a/tests/test_gt.py
+++ b/tests/test_gt.py
@@ -5,7 +5,7 @@
 from mcl import G1
 from mcl import Fr
 
-from . import test_data
+from tests import test_data
 
 
 class GTTests(unittest.TestCase):