I think I would stay away from hot glue for this application.
Craft stores often sell something that I think is called 'Blue Tak' - a plasticine-like putty that was targeted for college students who lived in dormitories where using tacks or other kinds of hangers to hang posters was not allowed. Blue-Tak can be kneaded to form a sticky adhesive-like material that could be used to hang things on the walls that could later be removed without any harm to the walls.
A small dab of Blue-Tak would hold items in place in a display without causing any harm to the items, and unlike silicone, it doesn't require any drying time - it sticks immediately.