I have a few small rubbermaid bins that I pack with me. one is for grooming tools, one's for grooming products, one's a first aid kit and so on.
For grooming tools I like to bring the basics, soft, medium and hard bristled brushes, rags, combs, sweat srapers, hoof picks, etc.
I also have a small kit with bands, my banding tools and braiding combs. This will also hold the hair clips I use when holding back hair on both manes and while I put in tails.
For grooming products I have Pepi spray, baby oil gel, braid tite, highlighters in clear and dark, hoof polish, polish remover, sometimes I have touch up spray. I'd have to look what other stuff I have, but those are my always haves. I put the dividers from wine boxes I get from the liquor store so everything is kept upright. I cut them off so they are the same height as the rubbermaid bin. I also keep the hoof polish in a ziplock baggie, just in case.
For my first aid kit, I have a box of people band-aids, tensor bandages, large guaze pieces, rolls of small and medium bandaging tape, vet rap, syringes, water bottles, rubbing alcohol, hydrogen peroxide, sanitary pads, a few small diapers (they work good on hocks and knees), anti-bacterial stuff, standing wraps, leg quilts, small lenghts of dowel for making splints, blood stop powder, duct tape, sponges (I get them from the dollar store), advil and tylenol. I keep small and large ziplock baggies for making ice packs, as well as old towels and face clothes to wrap them in.I sometimes add other stuff as well, but it starts feeling like alot of stuff to pack around and I think I've got almost all of the stuff I'd need for minor injuries.