Stay forward-looking, but hold on to your past. Please keep your first p oto- types. As souvenirs, these mementos will mean more than you know later on when you become the next Samsung. They are your first-born the something you made from nothing. Not to mention: You never know when you might go back to those early prototypes for a fresh reminder of your original vision.
If you make it through this gate, with ready prototypes in hand, you've come a long way. But the two most critical gates in building hardware startups are still ahead: Fund and Manufacture.