You’ll face three kinds of costs: money, time, and personal. They are intertwined—and. to some extent. interchangeable. If you think you cannot afford to hire a model-maker, for example, you may decide to save money by building it yourself at a cost of your time, which, in turn, often involves a personal cost to your health, your marriage, and so on, not to mention the fact that you may produce a poor model.

Be guided by this reality: if you think a pro is expensive, hire an amateur.