They are 6"x12" printed aluminum, lacquered with a few coats for weather protection.
After researching a little bit after I created this, it turns out there are only 19 states where you're allowed to have a decorative front license plate. All other states, you must have your actual plate.
This item will still look good in other places and I have a few more ideas in the works where this isn't connected to a vehicle.
The states where front decorative plates are allowed are:
The style of the license plate has 4 holes, so when looking for a frame is referred to as "4h slim". There are plenty of kits for installing also frames that look good with this I'll post below.