A number plate we made for the Sur-ron. My brother is the “Electric is better” guy on youtube and we are uploading the model here for anyone to use.
Over the years we changed the design slightly and added thicker sections, different mounting holes, etc..
I've printed well over 20 of these all on my Ender 3 Pro standing up with a brim and supports for the bottom mounting holes.
The version shown in the video below is the number plate v3.stl printed in Hatchbox PLA Black.
Here is an example of how you would support it in the slicer:
Below is a video of him talking about the plate.