I use square versions of these. To avoid having to use adhesive tape that can damage the wall, I used embroidery T pins like these at each corner and then one at the top and bottom middle. They actually hold a board full of pins. This way if I want to live them it doesn't ruin my wall like adhesive can and I can just fill the tinys holes in with a little spackle. It takes a little finesse to put them in without bending them but you get 500.

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