add 3D model preview window

app.py

@@ -479,7 +479,7 @@ def process_image_and_generate_stl(image_input, depth_near, depth_far, thickness
         lift_height=-lift
     )
 
-    return stl_path # Return the path to the generated STL file
+    return stl_path, stl_path # Return the path to the generated STL file
 
 
 # Gradio Interface definition
@@ -494,7 +494,10 @@ iface = gr.Interface(
         gr.Slider(minimum=0.01, maximum=0.1, value=0.01, label="BackSheet Thickness"),
         gr.Slider(minimum=0, maximum=0.1, value=0.0, label="lift"),
     ],
-    outputs=gr.File(label="Download STL File"), # Use gr.File() for file downloads
+    outputs=[
+        gr.File(label="Download STL File"),
+        gr.Model3D(label="STL Preview")
+    ], # Use gr.File() for file downloads
     title="Image to 2.5D Relief Model Generator",
     description="Upload an image, set parameters, and generate a 2.5D relief model (.stl file)."
 )