Small through hole cannot be cast in zinc metal die-casting process. All the small holes have to be manually drilled in order to fix the small parts and hinges. On some models, more than a hundred holes are needed to be drilled and each worker is assigned to drill only one hole at a time with a template. Small parts and hinges are then fixed with screws into holes. The screws are very small in size and the fixing is usually done by female workers with their delicate fingers.