It depends on the type of Ford oval you have.
Some are gel filled, some are 2 piece & some are pressed aluminum over a plastic base.
Here's a LINK
to my custom ovals page to give you some ideas.
I don't mod the gel filled ovals mostly due to the insane cost of epoxy to refill them & the fact that most epoxy will turn yellow after a short time in the sun.
The pressed metal ovals might be able to be painted, but you'd need to hand paint them.