We use a Tile on important/expensive things. My son has one on his iPad for school. Fortunately, we haven’t had to use it, because he’s good about putting it in his backpack when he leaves class — a rule we have been consistently pushing.
Can your son keep all these things in his car? His car could be the landing zone? Maybe a quick checklist in his car to help him double check that he has everything before he leaves where he is? If he has an iPhone, there’s a Find My Phone feature. You have to turn it on, but it’s very useful. I think Android has something similar.
ADDitude Community Moderator, Parenting ADHD Trainer & Author, Mom to teen w/ ADHD, LDs, and autism