I have an exhibition coming up but we are not allowed to screw into walls. I need a magnet that will hold card but also artwork in frames 20x20 and I will need the adhesive tape to be able to be removed without ruining the paint on the walls.
We recommend using the Magnart System, which you can find here.
It's one magnetic hanging system, the only difference is the quantity ie: 12 pack, 24 pack, 50 pack etc. Work out how many you need, will you use one in each corner – 4 to a hanging – or only the top two corners, two per hanging. Multiply that number by how many pictures you have and then purchase the set which will cover the required numbers.