diff --git a/src/main.py b/src/main.py
index b830c24..4992377 100644
--- a/src/main.py
+++ b/src/main.py
@@ -1,4 +1,4 @@
-import os, json, requests
+import os, json, requests, h5py
 from getpass import getpass
 from APIHandler import APIHandler
 from classes import *
@@ -200,6 +200,21 @@ def make_nexus_schema_dictionary(substrate_object, layers):
         }
     return pld_fabrication
 
+def build_nexus_file(pld_fabrication, output_path):
+    # NOTE: look at the mail attachment from Emiliano...
+    with h5py.File(output_path, "w") as f:
+        nx_pld_entry = f.create_group("pld_fabrication")
+        nx_pld_entry.attrs["NX_class"] = "NXentry"
+
+        # Sample section
+        nx_sample = nx_pld_entry.create_group("sample")
+        nx_sample.attrs["NX_class"] = "NXsample"
+
+        # Substrate section
+        nx_substrate = nx_pld_entry.create_group("substrate")
+        nx_substrate.attrs["NX_class"] = "NXsubentry"
+    pass
+
 if __name__=="__main__":
     # TO-DO: place the API base URL somewhere else. 
     ELABFTW_API_URL = "https://elabftw.fisica.unina.it/api/v2"