diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..8e4d20d
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "scad/common"]
+	path = scad/common
+	url = https://git.sixteenmillimeter.com/modules/common.git
diff --git a/scad/common b/scad/common
new file mode 160000
index 0000000..cba7a30
--- /dev/null
+++ b/scad/common
@@ -0,0 +1 @@
+Subproject commit cba7a3051ef0729eaa1d5c5da6205464185734e0