Initial Prototype
The initial prototype is a low-cost, low-fidelity way for you to reduce risk in the design process.
Before you build...
Here are a few things you should do (and write/draw/etc) before you build your prototype. We say "before," but there's a good chance you'll be doing this as you build as well, particularly for early prototypes like this one.
Overall Design Objective - What is the problem you are trying to solve? How will you know if you have solved it?
Prototype Design Objectives - What are you trying to accomplish with this prototype? What are you not trying to accomplish? When will you know you can move on to the next prototype?
Assumptions - What are you assuming about the user? About the environment the product will be used in? Anything else related to product use?
Bill of Materials - What are you using to build your prototype? (If purchased, include quantities, order links, and cost breakdown.)
"Technical Drawing" - Can be a CAD model, a wireframe, a hand-drawn sketch, a fabric pattern, a wiring diagram, and more! Include multiple views and detailed specifications and/or constraints (sizes, shapes, resistances, weights, etc) when possible. If you're using something like an obj or stl file (anything to be read by specific software), please also include an image of the item(s).
Testing, testing, 1, 2, 3...
That's a nice prototype you got there... it'd be a shame of someone were to... test it. (But no, actually, it wouldn't be. That's the point. Someone is testing it. You and your codesigner are testing it.)
Test Plan - How do you plan to test your prototype? What can you test by yourself, with your co-designer, or with others? Are there specific times or places that you need to pay attention to for testing?
Testing Pictures - If your tester(s) are okay with it, document your tests with pictures! Always be sure to ask for permission first, though.
Results - What happened? What did you learn? Detail any quantitative ("The plastic sleeve was 2 cm too long") and qualitative ("My codesigner had to strain her neck to reach the spot where her head was supposed to go") observations, as well as any direct user feedback.
... and what did we learn?
Prototype Conclusions - What did you learn from this iteration? Should you move on to a new prototype? What worked, and what needs to be tweaked or entirely redesigned?