The extension allows you to create your own product page layouts without having to edit the controller file. Install the extension and create a layout file. That's it - you don't need to edit any more files!
1. In the admin panel go to the section: "Extension - Installer".
2. Install the extension: custom_product_page_layouts_v1.0_opencart_X.x.ocmod.zip.
3. Update the modifier cache in the section: "Extension - Modifications".
4. Create a new layout file in the directory: catalog/view/theme/default/template/product/ (if you are using the default theme). You do NOT need to create a controller file.
5. Add a new layout in the admin panel in the section: "Design - Layouts". The path to the layout file is specified without the filename extension.
6. When editing a product in the "Design" section, select a new layout.