diff --git a/hasher-matcher-actioner/.devcontainer/devcontainer.json b/hasher-matcher-actioner/.devcontainer/devcontainer.json
index cfede72ec..635a8172a 100644
--- a/hasher-matcher-actioner/.devcontainer/devcontainer.json
+++ b/hasher-matcher-actioner/.devcontainer/devcontainer.json
@@ -43,10 +43,10 @@
     }
   },
   "remoteUser": "vscode",
-  "postCreateCommand": "pip install --editable .[all]",
   "mounts": [
     "source=python-threatexchange-cmdhistory,target=/commandhistory,type=volume",
     "source=${localEnv:HOME}${localEnv:USERPROFILE},target=/host-home-folder,type=bind,consistency=cached"
   ],
+  "postCreateCommand": "/workspace/.devcontainer/postcreate.sh",
   "postAttachCommand": "/workspace/.devcontainer/startup.sh"
 }
\ No newline at end of file
diff --git a/hasher-matcher-actioner/.devcontainer/postcreate.sh b/hasher-matcher-actioner/.devcontainer/postcreate.sh
new file mode 100755
index 000000000..ad6b20069
--- /dev/null
+++ b/hasher-matcher-actioner/.devcontainer/postcreate.sh
@@ -0,0 +1,11 @@
+#!/bin/bash
+set -e
+
+pip install --editable .[all]
+
+# Find Python packages in opt and install them
+for setup_script in "$(find /workspace/opt -name setup.py)"
+do
+    module_dir="$(dirname "$setup_script")"
+    pip install --editable "$module_dir"
+done
diff --git a/hasher-matcher-actioner/extensions/.gitignore b/hasher-matcher-actioner/extensions/.gitignore
new file mode 100644
index 000000000..72e8ffc0d
--- /dev/null
+++ b/hasher-matcher-actioner/extensions/.gitignore
@@ -0,0 +1 @@
+*
diff --git a/hasher-matcher-actioner/extensions/README.md b/hasher-matcher-actioner/extensions/README.md
new file mode 100644
index 000000000..533f7a452
--- /dev/null
+++ b/hasher-matcher-actioner/extensions/README.md
@@ -0,0 +1,3 @@
+# Optional Packages
+
+Drop any Python packages here which you need to be installed to the container but which can not be added to the `pyproject.toml`, e.g. proprietary extensions.