diff --git a/osbuild b/osbuild
index cbeb862b..66931efe 100755
--- a/osbuild
+++ b/osbuild
@@ -17,6 +17,9 @@ if __name__ == "__main__":
     parser = argparse.ArgumentParser(description="Build operating system images")
     parser.add_argument("pipeline_path", metavar="PIPELINE",
                         help="json file containing the pipeline that should be built")
+    parser.add_argument("--objects", metavar="DIRECTORY", type=os.path.abspath,
+                        default=".osbuild/objects",
+                        help="the directory where intermediary os trees are stored")
     requiredNamed = parser.add_argument_group('required named arguments')
     requiredNamed.add_argument("-i", "--input", dest="input_dir", metavar="DIRECTORY", type=os.path.abspath,
                         help="provide the contents of DIRECTORY to the first stage", required=True)
@@ -28,7 +31,7 @@ if __name__ == "__main__":
 
     with open(args.pipeline_path) as f:
         pipeline = json.load(f)
-    pipeline = osbuild.Pipeline(pipeline)
+    pipeline = osbuild.Pipeline(pipeline, args.objects)
 
     print()
     print(f"{RESET}{BOLD}Pipeline: {pipeline.id}{RESET}")
diff --git a/osbuild.py b/osbuild.py
index 63300819..7cf7190e 100644
--- a/osbuild.py
+++ b/osbuild.py
@@ -2,6 +2,7 @@
 import hashlib
 import json
 import os
+import shutil
 import subprocess
 import sys
 import tempfile
@@ -203,13 +204,16 @@ def print_header(title, options, machine_name):
     print()
 
 class Pipeline:
-    def __init__(self, pipeline):
+    def __init__(self, pipeline, objects):
         m = hashlib.sha256()
         m.update(json.dumps(pipeline, sort_keys=True).encode())
 
         self.id = m.hexdigest()
         self.stages = pipeline["stages"]
         self.assembler = pipeline.get("assembler")
+        self.objects = objects
+
+        os.makedirs(objects, exist_ok=True)
 
     def run(self, input_dir, output_dir, interactive=False):
         results = {
@@ -231,5 +235,12 @@ class Pipeline:
                     print_header(f"Assembling: {name}", options, buildroot.machine_name)
                 r = buildroot.run_assembler(self.assembler, tree, input_dir, output_dir, interactive)
                 results["assembler"] = r
+            else:
+                output_tree = os.path.join(self.objects, self.id)
+
+                shutil.rmtree(output_tree, ignore_errors=True)
+                os.makedirs(output_tree, mode=0o755)
+
+                subprocess.run(["cp", "-a", f"{tree}/.", output_tree], check=True)
 
         self.results = results
diff --git a/samples/base-qcow2.json b/samples/base-qcow2.json
index c9e14d8e..f328531f 100644
--- a/samples/base-qcow2.json
+++ b/samples/base-qcow2.json
@@ -4,7 +4,7 @@
     {
       "name": "io.weldr.untree",
       "options": {
-        "tree": "base-with-grub2"
+        "tree": "efc7b094c174d9f5fd66c863db7128415f5df0f073125716f5279554f13a659f"
       }
     }
   ],
diff --git a/samples/base-targz.json b/samples/base-targz.json
index f5cd5a0e..afddb1ff 100644
--- a/samples/base-targz.json
+++ b/samples/base-targz.json
@@ -4,7 +4,7 @@
     {
       "name": "io.weldr.untree",
       "options": {
-        "tree": "base"
+        "tree": "1f663f817473ffa5b01241b17adbd71bc734962313f5d4eef230073c0ac5884e"
       }
     }
   ],
diff --git a/samples/base-with-grub2.json b/samples/base-with-grub2.json
index 8a4d371e..ac3461e4 100644
--- a/samples/base-with-grub2.json
+++ b/samples/base-with-grub2.json
@@ -4,7 +4,7 @@
     {
       "name": "io.weldr.untree",
       "options": {
-        "tree": "base"
+        "tree": "1f663f817473ffa5b01241b17adbd71bc734962313f5d4eef230073c0ac5884e"
       }
     },
     {
@@ -15,11 +15,5 @@
 	"partition_table_id": "0xdeadbeef"
       }
     }
-  ],
-  "assembler": {
-    "name": "io.weldr.tree",
-    "options": {
-      "tree": "base-with-grub2"
-    }
-  }
+  ]
 }
diff --git a/samples/base-with-locale.json b/samples/base-with-locale.json
index d532d302..b64ba71f 100644
--- a/samples/base-with-locale.json
+++ b/samples/base-with-locale.json
@@ -2,9 +2,9 @@
   "name": "base-with-locale",
   "stages": [
     {
-      "name": "io.weldr.untargz",
+      "name": "io.weldr.untree",
       "options": {
-        "filename": "base.tar.gz"
+        "tree": "1f663f817473ffa5b01241b17adbd71bc734962313f5d4eef230073c0ac5884e"
       }
     },
     {
@@ -13,11 +13,5 @@
         "language": "en_US"
       }
     }
-  ],
-  "assembler": {
-    "name": "io.weldr.tree",
-    "options": {
-      "tree": "base-with-locale"
-    }
-  }
+  ]
 }
diff --git a/samples/base-with-selinux.json b/samples/base-with-selinux.json
index 81dd0936..11fcc9ce 100644
--- a/samples/base-with-selinux.json
+++ b/samples/base-with-selinux.json
@@ -4,7 +4,7 @@
     {
       "name": "io.weldr.untree",
       "options": {
-        "tree": "base"
+        "tree": "1f663f817473ffa5b01241b17adbd71bc734962313f5d4eef230073c0ac5884e"
       }
     },
     {
@@ -13,11 +13,5 @@
         "file_contexts": "etc/selinux/targeted/contexts/files/file_contexts"
       }
     }
-  ],
-  "assembler": {
-    "name": "io.weldr.tree",
-    "options": {
-      "tree": "base-with-selinux"
-    }
-  }
+  ]
 }
diff --git a/samples/base.json b/samples/base.json
index aaa479f1..eb19c34b 100644
--- a/samples/base.json
+++ b/samples/base.json
@@ -20,12 +20,5 @@
         ]
       }
     }
-  ],
-  "assembler":
-    {
-      "name": "io.weldr.tree",
-      "options": {
-        "tree": "base"
-      }
-    }
+  ]
 }