Alida from Alida Makes has a young daughter with a peanut allergy who needs to have an Epipen with her at all times. She created a toddler-sized backpack to hold the Epipen and some Benadryl. The backpack allows her to carry the medicine without impacting her ability to play like toddlers like to. Go to her tutorial to see how to make one.
[photo from Alida Makes]