Confidentiality Agreement
When submitting your idea to industry you should try to protect yourself with a Confidentiality Agreement-- A simple agreement that states that the people you are showing your concept to won't steal it outright. A lot of companies have their own policies on this matter and sometimes you have to play by their rules. This Sample Confidentiality Agreement is just here as an example of what one looks like. You can print it out and use it but we make no claims to its strength in court.
Design and Mechanical Patents
In a nutshell, designs cannot be copyrighted, but they can be patented. Mechanical patents can also be obtained. Most patent laws apply across international borders but there are some significant differences between the U.S.'s and other countries' application processes so do your research before starting the patent process.
To learn more about the fees associated with patents, who the trustworthy patent attorneys are and how to conduct online searches for patents you should check out the U.S. Patent and Trademark Office's WWW site.