Who doesn't love building prototypes? To witness an idea come to life is a truly amazing experience. When I can finally touch and hold an actual product in my hands, I'm in heaven!

But entrepreneurs need to be prudent. Building a prototype can become exceedingly time-consuming and expensive. Obsessing over the creation of a perfect prototype is not the best use of your time or energy, because no such thing exists. Prototypes are functional tools, not final products. And furthermore, licensing is a numbers game. If I were to focus on building a prototype for each of my ideas, I wouldn't get very far.

What I instruct my students to do instead is to showcase the benefit of their idea through a sell sheet. A sell sheet is a one-page advertisement for your idea. When you pitch a potential licensee, you're selling them on the benefit of your idea--not how it actually works. If the benefit of your idea isn't very strong, a potential licensee won't be interested. It's that simple. At this early stage, a prototype is not needed--3D computer-generated graphics are very realistic these days.

So, when should you invest in prototyping your idea?

1. When a potential licensee shows legitimate interest your idea. Before you send a company a prototype, you must qualify its request. At a minimum, you should have a dialogue with the company going. Even if you've spent just 10 to 15 minutes on the phone with an employee discussing your sell sheet, that's worlds away from having had no discussion at all. The company may need proof of concept. It might want to show your idea to a retail buyer to get its opinion. Or maybe it wants to conduct a focus group.

2. To make manufacturing improvements. Building a prototype should teach you about manufacturing, including what works and what doesn't. You can test out different materials and experiment with different designs.

3. To prevent workarounds. The intellectual property you file will be much stronger if you have thought about variations of your idea. Building a prototype is one way of doing that.

4. To film a video to include along with your sell sheet. People love watching video. It resonates with them. It's a powerful tool in your arsenal. For that reason, I recommend incorporating video in your sell sheet if you can. However, your prototype doesn't have to work perfectly or look great. You could cannibalize existing products to create it. The point is that there are ways of editing and filming your video so that your message gets across without a perfect prototype. And unlike an actual prototype, your video can never be broken or misplaced.

5. To help your patent attorney understand your invention. Does he or she get truly it? Some people need to hold a prototype to grasp what your idea is all about.

Building a prototype never fails to give me a sense of accomplishment. I've created something where there once was nothing, after all! If you're anything like me, you will feel a strong urge to build a prototype. Resist it. You cannot prototype each idea you have if you want to be successful. Never forget that what you're truly selling is the benefit of your idea. You do not need a prototype to convey the benefit of your idea.