I had to use tack strips on my drafting board way back when to keep people from leaning on it while I was inking a drawing. The sign didn’t work, but the tacks did.
I thought I had a bear visiting my property, twice, in the last week. Last night I found out it was a raccoon. Caught him climbing the deck where a door was open to cool the house. I might try some tack boards on the deck or the post he was climbing to discourage that. No risk of a person stepping on them doing that.