1. Garment OEM: There are some factories or processing factories specializing in garment OEM in Chengdu. You can contact these enterprises to find out whether they provide waist processing services. You can search related foundries through the Internet, or consult the local textile industry association for more information.

2. Tailor shops: On the streets of Chengdu, you can also find some tailor shops that provide various customized clothing processing services. You can consult local residents, or search nearby tailor shops through the Internet to see if there are waist processing services.

3. Clothing market: There are some large clothing markets in Chengdu, such as Chunxi Road and Kuanzhai Lane. These clothing markets usually have many small stalls and merchants, who provide various clothing processing and customization services. You can find businesses related to waist processing in these markets and discuss processing matters with them.