Hi there,
I heat press license plates all the time. I use Unisub plates and Artanium sublimation inks.
I have been doing them for years & they turn out great. There is also aluminum plates coated
for sublimation but I have not tried them. if you are not into sublimation, you will need an Epson inkjet printer that is compatible with sublimation inks and a regular heat press. I use a Hix clamshell.
If you need more info you can contact me again.
Lar