A simple thing for third party companies to make are trailers. They are essentially hollow plastic containers on wheels. This means there are a lot of them.
“thumb|right|300px|Nope, that's G3. It won't download your apps.When "FansProject" announced...G3 trailer
“The Trailer of 20th Anniversary OP is an add-on for Masterpiece Optimus Prime made by Justitoys...The Trailer of 20th Anniversary OP