Well if they wanted they could just out right replace the caps when
stealing or tape over. When I did art on a cart- I literally only
had the joined supplies for the whole school. So there was no "my
art supplies". What I did do was to pass out the lesson with
material included; i.e.,Materials supplied by students/classroom and
materials I supplied/or already supplied. For instance a lesson
Materials supplied by students: Scissors,glue etc.
Then I'd say materials supplied: paper,stencils, paint brushes etc.
I would place the lesson in their mail box- perhaps this was too
much of an undertaking for you all but it helped me. You could try