With 6 cats who exhibit varying degrees of “badness,” we struggle with keeping them from exploring anything new, like say a tree with shiny, dangling objects on it. To keep the cats away from the Christmas tree, my husband put a can of SSSCAT Spray near the base. Here is the product description: “Keep your cat off of furniture, countertops, and plants. SSSCAT Spray senses your cat within 1 meter, then emits a startling, deterring spray. Contains odorless, non-staining gas, harmless to pets and people. Approximately 120 sprays per can.”
It worked beautifully for keeping cats away from the Christmas tree. When they got close, it made a sharp “pssst” noise with a burst of the harmless mystery gas and the cats would scatter. The downside was that I set it off three times that evening and my blood-pressure was through the roof. But, fortunately we found that it worked even if it wasn’t turned on. When I saw Benjamin, the biggest nibshit, walking toward the tree, I made a “PSSST” sound and he took off running :). From that moment on he has given the tree a wide berth.