If you are looking to have car bumpers modified or customized in China, you have several options to explore:

1. Custom Automotive Shops: Many automotive shops, especially those specializing in customizations and modifications, offer services for modifying car bumpers. These shops can help design, fabricate, and install custom bumper modifications to suit your preferences.
2. Specialty Body Shops: Body shops that specialize in collision repair and automotive bodywork may also offer customization services. They can help modify or repair existing bumpers or create custom designs.
3. Online Customization Services: Some online platforms and companies offer customization services for various automotive components, including bumpers. You can submit your specifications and preferences, and they will produce and ship the modified bumper to you.
4. Automotive Shows and Events: Attending automotive shows, expos, and events in China can provide an opportunity to connect with custom automotive shops and manufacturers specializing in bumper modifications. You can see their work in person and discuss your specific needs.
5. Local Fabrication and Welding Workshops: Some fabrication and welding workshops may have the capability to modify or create custom bumper designs. They can work with various materials, such as metal or plastic, to achieve the desired look.
6. Online Marketplaces: Some online marketplaces and classified websites might have listings from individuals or businesses offering bumper modification services. Be cautious when using such platforms, and thoroughly research the service providers before making any commitments.

When seeking bumper modification services, consider the following:

• Research the reputation and experience of the service provider.
• Provide clear specifications and expectations for the modification.
• Discuss design ideas and material choices with the service provider.
• Request price quotes and compare them from different sources.
• Inspect the work quality and ensure that it meets your expectations before finalizing the project.

It’s important to work with skilled professionals or reputable shops to ensure that the modified bumpers are not only aesthetically appealing but also structurally sound and safe for your vehicle. Additionally, be aware of any legal and safety regulations related to vehicle modifications in your area.