I had my share of physical products prototyping, from books to physical pieces but I will focus more on the digital part.

While I love paper prototyping I rarely have the chance to use it. Digital deliverables are always in order or the clients feel they are not getting their moneys worth. So I obviously resort to several tools available to make it work. I have prototyped in dedicated apps like Pop (mobile app), Axure and Invision but I have used my share of Keynote or pdf prototyping also. I have also work for proof of concepts apps with engineers and we built them directly on Xcode.

visual design

Proof of concept directly on Xcode

Invision prototypes

Axure prototyping

Keynote prototyping