Invention? - Fort Worth,TX

Yes, I have. You can do a patent search on USPTO website and see if someone else already came up with the idea.
Then call one of the Universities that has an intellectual law clinic and see if they will file your patent for free - this is how I got my patent.
Get a 3 D model/CAD design of the product and have a prototype made for testing.
To manufacture go to www.mfg.com, submit your drawings and you will find a manufacturer
Google SCORE online and request a free mentor that can take you step by step into the process.
Do not share your product idea with anyone except those that sign a non disclosure agreement
Visist Mom Invented website by Tamara Monosof
Mom Invented: Business Advice & Inventing Help for Women ...
www.mominventors.com/
Read the Mom Inventors Handbook by Tamara Monosof
Any questions Private message me
My business is Nurseborn, products created by nurses

Unfortunately, mailing something to yourself ("The Poor Man's Copyright") does not give any legal protection to you or your invention. That is a myth and is completely useless.

You need to get a patent. http://www.uspto.gov/

There are detailed instructions on that site. You can also search current patents.

My father told me that before you show anything to anyone in the process of getting it published or produced, document everything about it in as much detail as possible then seal everything up in an envelope and send it registered mail to yourself. That way if there is a dispute later on down the line about who came up with the idea first, you have a sealed and dated time capsule to prove your validity. I've never had opportunity to make use of this advice so take from it what you will.

even if you do what nicole says unless its patented people can still use your idea.
you have to have a good amount of money to invest ot make anything

You could do as Nicole says. You may want to send multiple copies. And make sure you keep a copy and know exactly what is in that sealed envelope. You don't want to break the seal until you have to.
You could also get a patent. This is a bit of a process though.
If you take your idea to ANYONE, have them sign a non-disclosure agreement. You can find them online.
Just beware, no matter what you do, non-U.S. companies (China, etc) often steal these ideas and get them to market before you can even blink. And it's nearly impossible to fight without spending a lot of money.
Good luck.

You can do what Nicole says but unfortunatelly, the law have changed in the US and now even if you came up with the idea first the one that gets the rigths is the one that pantented first (in the past if you could prove that you had the idea first but didn't patented first you own the rights). Is a dificult path because there is a lot scammers, beware. You are lucky that Liv commented on your question and you can asker her because she already went through this long journey. I tried to go this path but gave up because my creation was more of a fashion thing and is difficult not to be copied and even having a patent does't guarantee me that. Is a dificult economy to risk my savings. God Bless you in your journey!