1. size: the width of the door you said is 4 meters, which means you can make full use of this space to design a spacious and eye-catching house number.

2. Materials: It is very important to choose durable and reliable materials. Common materials are metal, plastic, glass, etc. You can choose suitable materials according to your budget and design requirements.

3. Fonts and images: It is very important to choose easy-to-read and attractive fonts and images for the door signs. Fonts should be clear and easy to identify, while images or logos should be relevant to your business and attract people's attention.

4. Lighting: Proper lighting can improve the visibility and attractiveness of house numbers. You can consider using LED lights or other lighting equipment to ensure that house numbers can be seen at any time.

5. Color matching: Choosing a suitable color matching scheme is very important for the design of the door signboard. You can choose the right color according to your own brand image and business type to make the signboard at the door more prominent and attractive.

In addition to the above elements, you can also consider adding some additional decorative elements, such as chandeliers, flower baskets or other decorations, to increase the uniqueness and attraction of the signboard at the door.

In a word, many factors need to be considered in the design of the door signboard, including size, material, font and image, lighting and color matching. I suggest you consult a professional designer or a doorplate manufacturer for more specific and personalized advice.