diff --git a/openfoam/run/__main__.py b/openfoam/run/__main__.py
index 67b9ef2..37a20c3 100644
--- a/openfoam/run/__main__.py
+++ b/openfoam/run/__main__.py
@@ -14,6 +14,7 @@ import subprocess as sp
 import urllib.error
 
 from .grafana import Silencer
+from .stl import copy_stl
 
 
 _t0 = time()
@@ -68,13 +69,8 @@ if config.getboolean('stl', 'copy', fallback=False):
         log.error(f'STL from directory does not exist ({stl_in})')
         sys.exit(1)
 
-    stl_dir = case_dir.joinpath('constant', 'triSurface')
-    if stl_dir.exists():
-        log.info(f'Deleting stl directory ({stl_dir})')
-        shutil.rmtree(stl_dir)
-
-    log.info(f'Copying stl directory ({stl_in} -> {stl_dir})')
-    shutil.copytree(stl_in, stl_dir)
+    log.info(f'Copying stl directory ({stl_in})')
+    copy_stl(stl_in, case_dir)
 
 if config.getboolean('blockMesh', 'enable', fallback=False):
     log.info('Running blockMesh')
diff --git a/openfoam/run/stl.py b/openfoam/run/stl.py
new file mode 100644
index 0000000..b932bd4
--- /dev/null
+++ b/openfoam/run/stl.py
@@ -0,0 +1,13 @@
+import shutil
+import logging
+
+log = logging.getLogger('stl')
+
+def copy_stl(stl, case):
+    stl_dir = case.joinpath('constant', 'triSurface')
+    if stl_dir.exists():
+        log.info(f'Deleting stl directory ({stl_dir})')
+        shutil.rmtree(stl_dir)
+
+    log.info(f'Copying stl directory ({stl} -> {stl_dir})')
+    shutil.copytree(stl, stl_dir)