Band-aids. For those real wounds and not so real wounds.
I didn't tell my class this up front, but I put a container of band-aids at the back of the room. When someone asked, I told them where to get one.
I really thought if I told the students up front, they would have to suddenly get band-aids all the time. You know those classes, right?
They manage to open and put the band-aids on just fine by themselves.