You can do what you like with whatever you fancy to your machines... copyright is only an issue when it becomes a commercial entity.
Copyright is also only an issue if someone is prepared to do anything about it.
WG made it a lifestyle.. especially for Australians....... he let so many USA deals go unhindered it was unreal.
Licensed materials or reproductions are SUPPOSED to guarantee a level of quality that the reproduction is true to original and of same quality or better.
Unfortunately, this does not apply to many licenced products available.
Who really cares if you print some decals for your machine??
