Product customizer with CMYK needed!

[G-G-B3]

Hello, I am looking for the product customizer (design tool and advanced product options) with CMYK options.

CMYK based file is needed for us to print.  

I've found a design tool which supports CMYK but they do not offer product options.

So, it seems like I need to hire someone to customize the app which use RGB.

I've contacted to a few companies, and they said their app cannot be customized so I am lost here.

Any ideas of the app which can be customized, or supports CMYK file options?

No RGB options will be needed.