Hello,
We recommend coloring the product only after it has been fully assembled and tested to ensure all functions are working properly. This will help prevent any issues that might arise from painting earlier.
You can use acrylic paint for coloring.
Then your opinion definitely means more than mine here, because you’ve painted so many more kits and you’ve already painted the pinball itself too 
. It’s really helpful to know it still works perfectly when done that way, and your result looks amazing you know heheh