As a design student we are often ask to do prototype prototype prototype. But many of us always have this wrong conception of doing one prototype to test out our ideas and also to show our professor was enough. Learning from what the book mention, it is always beneficial for us – the designers to create more prototype. We can even do simple dirty prototype created by paper or even sketches. It is definitely plus point if you could do amazing sketches but most importantly like the book mentions, finding the purpose of the sketch. if it helps you to convey ideas or jot down the way of improvement then nice sketches is not always essential.
Also it always not always about spending huge amount of money, but more of letting the designer observed how the prototype i being use and what people experience with it are. An interesting topic mention in the book is movie prototype. We often think about it as creating a video, creating an animation or promotional video for our product. But not necessarily think of these videos as prototype. Actually the function and purpose of the videos are similar to the 3D prototype we create, it helps us to easier convey our ideas to clients and also showing the user perspective of it.