Hi teacher,
I have some insight into your question:
Unfortunately, this sort of thing gets expensive quite quickly. The first item you must know is that to patent something, it must meet the following requirements:
1. It must be novel, i.e. there can be no "prior art," essentially this means that if you apply for a patent, a patent examiner is going to search long and hard for some way to discredit your invention as already existing in some shape or another. Even something as trivial as a drawing on the back of a cocktail napkin can count against you as prior art. Also, if your invention uses somebody else's patented invention, you must get their permission (and you must be careful in discussing your ideas with them and others as they could easily steal it and pursue patents on it as their own). This concept differs between getting protection in the U.S. versus getting protection in the rest of the world (rest of the world requires absolute novelty while the U.S. gives you one year after public disclosure of your invention before you must file an application)
2. non-obvious, i.e. you cant take a previous invention and try to patent an obvious application or modification to it
3. useful, your invention should have no problem qualifying as useful so i wouldnt worry about this category
Patent costs can be quite pricey, and generally include the hiring of a patent attorney to determine patentability. Typical costs of this include:
patent search $400 - $500+
patentability opinion $1,500 – $2,000
Freedom to Operate/Right to Practice opinion $2,500+
prepare patent application $8,000+ (U.S. only)
Thus, inventors often try to sell their invention to companies to avoid as much of this as possible. Getting your foot in the door with companies might not be easy but if you do, just make sure you only discuss your invention with them under one of the following conditions:
1. be sure you only give them a non-enabling disclsure (i.e. you discuss what the thing does but not how you make it or how it does it)
or
2. Have them sign a non-disclosure agreement
In addition, depending on where you work, you may have signed an agreement upon your employment that the company owns any intellectual property created by you while you work there. Make sure this isn't the case or that you have permission from them to pursue this as your own before you go any farther.
Sorry if this paints a bleak picture, and sorry for the pages and pages of info I left out, but I think this gives you the general idea that it is not quite "simple" to patent something. Nonetheless, if you have any specific questions, I would be happy to answer them. If you have some free time, poke around the USPTO website (United States Patent and Trademark Office) and google related terms for more info. Good luck!!
P.S.
I just realized I didn't fully respond to two things mentioned by you and sue:
1. "working models" are no longer required as the USPTO already has a huge building full of the working models of previous inventions and simply doesn't have room. In your application, you need simply to "enable" the invention, i.e. explain with words and drawings exactly how it works and what the best way to make it is. However, if an examiner disputes your explanation, having a working model on hand would be a quick way to prove him wrong!
2. "Patent pending" can only be used if you have a patent application filed and are waiting for a response. It offers no real protection, but tends to deter competition as they will assume a patent is on its way so there is no use in copying your invention (by the time they get their version to market, your patent might have issued and they will be unable to sell their product). You still have to have gone through the process (and cost) of applying for a patent before you are legally allowed to use "patent pending" on a product