Android Question Use multi resource in app

[Bel]

Hi
I programming app for a shop
I want to sell it to other client.
Each client have a resource (drawable,string.xml,layout)
I need to compile app with client's resourse
I cannot use BuildConfiguration
I need to use CustomBuildAction in my project to copy resourse in object folder
look at the picture :

up folder is different for each client
please help me
Thanks