Easytiger, you are correct. However you must be able to prove the origin date you produced the drawings, photos, etc. Ones "word" is not sufficient.

Dating and signing your works will provide a legal edge if copying is done. The Library of Congress instructs the author should state on their original works "Copyright (copyright circle C emblem) Date by (Author's name). This provides about 50% legal protection. The remaining 50%, which seals the copyright protection requires the author to either (1) register the documents, with copies, to the Library of Congress, or (2) seal copies in an envelope and mail to one self. The mailed copy must remain sealed to be legitimate. The postmark establishes the copyright date.

I doubt many of the model designers (or other folks) ever take the second step, therefore have little recourse unless they want to spend considerable time "proving" they are the true copyright holder.

Having the first step appear on your drawings, etc., will usually keep Copy Centers from reproducing a visibly annotated document.

Not completing step two only leaves you with whining rights or an expensive legal pursuit if someone purloins your works.