diff --git a/pyproject.toml b/pyproject.toml
index e0aad04..aa0ebb8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,7 +1,7 @@
 
 [project]
 name = "jo3util"
-version = "0.0.2"
+version = "0.0.3"
 description = ""
 dependencies = []
 dynamic = ["readme"]
diff --git a/src/eqx.py b/src/eqx.py
index 41e63d8..ab11538 100644
--- a/src/eqx.py
+++ b/src/eqx.py
@@ -1,10 +1,12 @@
 #! /usr/bin/env python3
 
-from typing import Callable, Optional
+from typing import Callable, Optional, Tuple
 
 import equinox as eqx
+import jax
 
 from .fn import compose
+from .warning import todo
 
 
 def create_hook(
@@ -42,3 +44,72 @@ def create_hook(
         return Hook(node)
 
     return _create_hook
+
+
+def sow(where: Callable, model: eqx.Module) -> eqx.Module:
+    """Capture intermediate activations that the argument modules output
+    and return them together after model output"""
+    activ = []
+
+    def install_sow(node: Callable):
+        node_call = type(node).__call__
+
+        if isinstance(node, eqx.Module):
+            todo("make StoreActivation a generic class")
+
+            class StoreActivation(type(node)):
+                def __init__(self, node):
+                    self.__dict__.update(node.__dict__)
+
+                def __call__(self, *args, **kwargs):
+                    x = node_call(self, *args, **kwargs)
+                    activ.append(x)
+                    return x
+
+            return StoreActivation(node)
+
+        else:
+
+            def store_activation(*args, **kwargs):
+                x = node(*args, **kwargs)
+                activ.append(x)
+                return x
+
+            return eqx.filter_jit(store_activation)
+
+    model = eqx.tree_at(where, model, replace_fn=install_sow)
+
+    model_call = type(model).__call__
+    todo("make Sow a generic class")
+
+    class Sow(type(model)):
+        def __init__(self, model):
+            self.__dict__.update(model.__dict__)
+
+        def __call__(self, *args, **kwargs):
+            activ.clear()  # empty the list
+            x = model_call(self, *args, **kwargs)
+            return x, activ
+
+    return Sow(model)
+
+
+def insert_after(where: Callable, model: eqx.Module, func: Callable) -> eqx.Module:
+    """Place a callable immediately after the argument modules"""
+
+    class Ensemble(eqx.Module):
+        children: Tuple
+
+        def __init__(self, node):
+            self.children = (node, func)
+
+        def __call__(self, *args, **kwargs):
+            x = self.children[0](*args, **kwargs)
+            x = self.children[1](x)
+            return x
+
+        def __getitem__(self, items):
+            return self.children[items]
+
+    model = eqx.tree_at(where, model, replace_fn=Ensemble)
+    return model
diff --git a/src/warning.py b/src/warning.py
new file mode 100644
index 0000000..bf9781b
--- /dev/null
+++ b/src/warning.py
@@ -0,0 +1,18 @@
+#! /usr/bin/env python3
+# vim:fenc=utf-8
+
+"""
+
+"""
+
+import warnings
+
+class ToDoWarning(Warning):
+    def __init__(self, msg):
+        self.message = msg
+
+    def __str__(self):
+        return repr(self.message)
+
+def todo(msg):
+    warnings.warn(msg, ToDoWarning)