Producing a model or prototype will help you find a very good way to manufacture the unit you have invented. It may be helpful for all kinds of things like figuring out where you can put labels, what the shipping weight will probably be, how to best package it, what it really may cost to fabricate it, also to get feedback from test users. It is a valuable tool to help you.
If you are intending to attempt to raise money to produce the brand new product yourself, or maybe you're demonstrating it to a possible client to get a big order, you will need the prototype if you don't already have a production unit to show or demonstrate.
People just don't have much imagination. You are an inventor, and that means you do have an imagination. Before you can invent something you want the idea...and it takes imagination to come up with great new ideas. Other people, you will find, simply do do not have the imagination or vision that you simply do. Assist them.
With a good prototype or model, your audience needn't provide an imagination. It can make cool product "real" on their behalf, adding tremendously in your credibility. Having a good prototype will help sell the merchandise even though it is not even in production yet.
DON'T delay prototype building until when you file your patent application. You will likely discover flaws or extra features, or discover possible manufacturing problems. With rare exception prototyping is quite worthwhile. There are almost always unexpected discoveries from construction of InventHelp prototype service.
Tests are very important. A prototype allows you to actually test your invention inside a meaningful way. You can attempt it with folks apart from yourself if appropriate, and you will then realize that other people will have constructive criticisms and suggestions that could be very valuable.
By searching online you will find model and prototype building companies who is able to construct it for you personally if you do not have the skills yourself.
There are instances when a prototype is not practical, when it is too costly for example, however, if it's you can, I highly recommend an invention prototype or model be manufactured.