diff --git a/ptycho/__init__.py b/ptycho/__init__.py
index e69de29..6aceeef 100644
--- a/ptycho/__init__.py
+++ b/ptycho/__init__.py
@@ -0,0 +1,3 @@
+from .ptycho_base import PtychoEngine
+from .ptycho_example import ExamplePtychoEngine
+from .fold_slice import FoldSlicePtychoEngine
\ No newline at end of file