diff --git a/src/builder.rs b/src/builder.rs
index 0f85bd1ac..c8c0cdc55 100644
--- a/src/builder.rs
+++ b/src/builder.rs
@@ -3,7 +3,7 @@
 use thiserror::Error;
 
 #[cfg(feature = "pyo3")]
-use pyo3::prelude::*;
+use pyo3::{create_exception, exceptions::PyException, PyErr};
 
 use crate::hugr::{HugrError, Node, ValidationError, Wire};
 use crate::ops::handle::{BasicBlockID, CfgID, ConditionalID, DfgID, FuncID, TailLoopID};
@@ -78,11 +78,18 @@ pub enum BuildError {
     CircuitError(#[from] circuit::CircuitBuildError),
 }
 
+#[cfg(feature = "pyo3")]
+create_exception!(
+    pyrs,
+    PyBuildError,
+    PyException,
+    "Errors that can occur while building a Hugr"
+);
+
 #[cfg(feature = "pyo3")]
 impl From<BuildError> for PyErr {
     fn from(err: BuildError) -> Self {
-        // We may want to define more specific python-level errors at some point.
-        PyErr::new::<pyo3::exceptions::PyRuntimeError, _>(err.to_string())
+        PyBuildError::new_err(err.to_string())
     }
 }
 
diff --git a/src/hugr.rs b/src/hugr.rs
index 648383562..831f16298 100644
--- a/src/hugr.rs
+++ b/src/hugr.rs
@@ -23,7 +23,7 @@ use portgraph::{Hierarchy, NodeIndex, PortMut, UnmanagedDenseMap};
 use thiserror::Error;
 
 #[cfg(feature = "pyo3")]
-use pyo3::prelude::*;
+use pyo3::{create_exception, exceptions::PyException, pyclass, PyErr};
 
 pub use self::views::HugrView;
 use crate::extension::{
@@ -463,11 +463,18 @@ pub enum HugrError {
     InvalidNode(Node),
 }
 
+#[cfg(feature = "pyo3")]
+create_exception!(
+    pyrs,
+    PyHugrError,
+    PyException,
+    "Errors that can occur while manipulating a Hugr"
+);
+
 #[cfg(feature = "pyo3")]
 impl From<HugrError> for PyErr {
     fn from(err: HugrError) -> Self {
-        // We may want to define more specific python-level errors at some point.
-        PyErr::new::<pyo3::exceptions::PyRuntimeError, _>(err.to_string())
+        PyHugrError::new_err(err.to_string())
     }
 }
 
diff --git a/src/hugr/serialize.rs b/src/hugr/serialize.rs
index c75afa2af..53bff8cc6 100644
--- a/src/hugr/serialize.rs
+++ b/src/hugr/serialize.rs
@@ -6,7 +6,7 @@ use std::collections::HashMap;
 use thiserror::Error;
 
 #[cfg(feature = "pyo3")]
-use pyo3::prelude::*;
+use pyo3::{create_exception, exceptions::PyException, PyErr};
 
 use crate::extension::ExtensionSet;
 use crate::hugr::{Hugr, NodeType};
@@ -89,10 +89,18 @@ pub enum HUGRSerializationError {
     FirstNodeNotRoot(Node),
 }
 
+#[cfg(feature = "pyo3")]
+create_exception!(
+    pyrs,
+    PyHUGRSerializationError,
+    PyException,
+    "Errors that can occur while serializing a Hugr"
+);
+
 #[cfg(feature = "pyo3")]
 impl From<HUGRSerializationError> for PyErr {
     fn from(err: HUGRSerializationError) -> Self {
-        PyErr::new::<pyo3::exceptions::PyRuntimeError, _>(err.to_string())
+        PyHUGRSerializationError::new_err(err.to_string())
     }
 }
 
diff --git a/src/hugr/validate.rs b/src/hugr/validate.rs
index 9db0a4f7b..281fb80c9 100644
--- a/src/hugr/validate.rs
+++ b/src/hugr/validate.rs
@@ -10,7 +10,7 @@ use portgraph::{LinkView, PortView};
 use thiserror::Error;
 
 #[cfg(feature = "pyo3")]
-use pyo3::prelude::*;
+use pyo3::{create_exception, exceptions::PyException, PyErr};
 
 use crate::extension::SignatureError;
 use crate::extension::{
@@ -636,11 +636,18 @@ pub enum ValidationError {
     SignatureError { node: Node, cause: SignatureError },
 }
 
+#[cfg(feature = "pyo3")]
+create_exception!(
+    pyrs,
+    PyValidationError,
+    PyException,
+    "Errors that can occur while validating a Hugr"
+);
+
 #[cfg(feature = "pyo3")]
 impl From<ValidationError> for PyErr {
     fn from(err: ValidationError) -> Self {
-        // We may want to define more specific python-level errors at some point.
-        PyErr::new::<pyo3::exceptions::PyRuntimeError, _>(err.to_string())
+        PyValidationError::new_err(err.to_string())
     }
 }
 
diff --git a/src/hugr/views/sibling_subgraph.rs b/src/hugr/views/sibling_subgraph.rs
index a48ca2978..6d9e6e67d 100644
--- a/src/hugr/views/sibling_subgraph.rs
+++ b/src/hugr/views/sibling_subgraph.rs
@@ -26,6 +26,9 @@ use crate::{
 
 use super::HugrView;
 
+#[cfg(feature = "pyo3")]
+use pyo3::{create_exception, exceptions::PyException, PyErr};
+
 /// A non-empty convex subgraph of a HUGR sibling graph.
 ///
 /// A HUGR region in which all nodes share the same parent. Unlike
@@ -536,6 +539,21 @@ pub enum InvalidReplacement {
     NonConvexSubgraph,
 }
 
+#[cfg(feature = "pyo3")]
+create_exception!(
+    pyrs,
+    PyInvalidReplacementError,
+    PyException,
+    "Errors that can occur while constructing a SimpleReplacement"
+);
+
+#[cfg(feature = "pyo3")]
+impl From<InvalidReplacement> for PyErr {
+    fn from(err: InvalidReplacement) -> Self {
+        PyInvalidReplacementError::new_err(err.to_string())
+    }
+}
+
 /// Errors that can occur while constructing a [`SiblingSubgraph`].
 #[derive(Debug, Clone, PartialEq, Eq, Error)]
 pub enum InvalidSubgraph {
diff --git a/src/std_extensions/rotation.rs b/src/std_extensions/rotation.rs
index 15e1da725..35b2102b9 100644
--- a/src/std_extensions/rotation.rs
+++ b/src/std_extensions/rotation.rs
@@ -8,7 +8,7 @@ use num_rational::Rational64;
 use smol_str::SmolStr;
 
 #[cfg(feature = "pyo3")]
-use pyo3::prelude::*;
+use pyo3::{pyclass, FromPyObject};
 
 use crate::extension::ExtensionId;
 use crate::types::type_param::TypeArg;
diff --git a/src/types.rs b/src/types.rs
index 21688d936..86a44a777 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -13,6 +13,7 @@ pub use custom::CustomType;
 pub use signature::{FunctionType, Signature, SignatureDescription};
 pub use type_row::TypeRow;
 
+use derive_more::{From, Into};
 use itertools::FoldWhile::{Continue, Done};
 use itertools::Itertools;
 use serde::{Deserialize, Serialize};
@@ -24,8 +25,10 @@ use std::fmt::Debug;
 
 use self::primitive::PrimType;
 
+#[cfg(feature = "pyo3")]
+use pyo3::pyclass;
+
 /// The kinds of edges in a HUGR, excluding Hierarchy.
-//#[cfg_attr(feature = "pyo3", pyclass)] # TODO: Manually derive pyclass with non-unit variants
 #[derive(Clone, PartialEq, Eq, Debug, serde::Serialize, serde::Deserialize)]
 #[non_exhaustive]
 pub enum EdgeKind {
@@ -46,6 +49,12 @@ impl EdgeKind {
     }
 }
 
+/// Python representation for [`EdgeKind`], the kinds of edges in a HUGR.
+#[cfg_attr(feature = "pyo3", pyclass)]
+#[repr(transparent)]
+#[derive(Clone, PartialEq, Eq, Debug, From, Into)]
+pub struct PyEdgeKind(EdgeKind);
+
 #[derive(
     Copy, Default, Clone, PartialEq, Eq, Hash, Debug, derive_more::Display, Serialize, Deserialize,
 )]
@@ -167,6 +176,7 @@ impl TypeEnum {
 )]
 #[display(fmt = "{}", "_0")]
 #[serde(into = "serialize::SerSimpleType", from = "serialize::SerSimpleType")]
+#[cfg_attr(feature = "pyo3", pyclass)]
 /// A HUGR type - the valid types of [EdgeKind::Value] and [EdgeKind::Static] edges.
 /// Such an edge is valid if the ports on either end agree on the [Type].
 /// Types have an optional [TypeBound] which places limits on the valid
diff --git a/src/types/signature.rs b/src/types/signature.rs
index 0e83f4037..076ba8815 100644
--- a/src/types/signature.rs
+++ b/src/types/signature.rs
@@ -1,7 +1,7 @@
 //! Abstract and concrete Signature types.
 
 #[cfg(feature = "pyo3")]
-use pyo3::prelude::*;
+use pyo3::{pyclass, pymethods};
 
 use std::ops::Index;
 
diff --git a/src/types/type_row.rs b/src/types/type_row.rs
index 055a5ac6d..b3b69bafe 100644
--- a/src/types/type_row.rs
+++ b/src/types/type_row.rs
@@ -11,9 +11,12 @@ use super::Type;
 use crate::utils::display_list;
 use delegate::delegate;
 
+#[cfg(feature = "pyo3")]
+use pyo3::pyclass;
+
 /// List of types, used for function signatures.
 #[derive(Clone, PartialEq, Eq, Debug, serde::Serialize, serde::Deserialize)]
-//#[cfg_attr(feature = "pyo3", pyclass)]
+#[cfg_attr(feature = "pyo3", pyclass)]
 #[non_exhaustive]
 #[serde(transparent)]
 pub struct TypeRow {