I’ve taken to carrying a small bottle of hand sanitizer, some q tips and a couple of band aids in a travel soap dish. When you bust your knuckle or otherwise break your protective outer covering the hand sanitizer will disinfect it and help get any dirt and debris out. The Q-tips are to lift severed patches of skin and get the dirt out from underneath.
The soap dish can also act as a handy nut and bolt holder, too. Taking the nuts and bolts that belong with something with you is easier than trying to scrounge through your own parts to find something that matches. If you buy multiples, you can even label them with sharpie (e.g: '95 VW intake bolts) and duct tape them to your part.
Hand sanitizer will also work as a degreaser in a pinch.
