In the early days of the United States patent system, every inventor had to make a prototype or working model of their invention to present to the US patent office during the application process. This standard no longer applies for patent applications, but it is still wise to build a prototype for a number of reasons.
The first is that a prototype provides a legal “reduction to practice” and can be used as proof in court that you invented the product first. Another good reason to build a prototype is that you can take pictures of it to include in your inventor’s logbook. It can help you to figure out flaws in the design of your invention as well, and allow you to test it under different conditions to work out the bugs. Moreover, a prototype is a useful tool for selling and licensing an invention, and it can be used during demonstrations and presentations. Potential buyers and licensees will be more easily influenced with a working model that they can see, touch and test.
There are different approaches to prototype creation. An inventor can build a prototype on their own, which is usually the cheapest option. As long as your prototype can demonstrate the look, feel and function of your invention, it is probably best to create it yourself. If your product is more complex and skilled tradespeople to manufacture it then it’s probably worth paying for their services.
You can start out by checking with independent local shops which may be used to handling prototype requests. Skilled tradespeople like welders can work on a time and materials basis, but be aware that this may cost you up to $100 per hour. You may even be able to get auto repair shops to do some of this kind of work for you as well.