Some good ideas to include in a stress relief kit can be traditional, like soothing music or herbal tea remedies. Offbeat items like a clickable pen or bubble wrap can help the stressed person relieve some tension too.
Aromatherapy is a popular way to relax, whether you add scented candles, essential oils, or a piece of jewelry that has aromatherapy in it. Puzzles and toys that relieve tension work great, as well as snacks, chewing gum, or anything orange, which is said to elevate the mood (source).