diff --git a/TODO.txt b/TODO.txt
index 6d6aba5b..0babd4b4 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -44,4 +44,7 @@ o Advanced Transformations
   - Add statement for 2D and 3D minkowski sum
   - Add statement for refinement via surface subdivision
   - Add statement for intersections in cartesian product of childs
+o Function-Module-Interface
+  - Pass a module instanciation to a function (e.g. for a volume() function)
+  - Pass a function to a module instanciation (e.g. for dynamic extrusion paths)