They’re so light that I can’t see them

Do you have pics?

Yes pictures please!

Do you have an outdoor area where they could serve their intended purpose as plant stands?

They would work and look nice with a nice trailing Pothos ... but cat! Maybe sell them or put away for when you might be able to use them as plant stands. Is there a room the can't doesn't have access to?

Could you fasten them to a board which would go under the legs of the stand. Make the board 1 inch by 15 inches or bigger so that the stand won't tip. You may have to fasten the pot on top so it doesn't move somewhat. Cats can be climbers and knock a lot of things over. The bottom board I would paint black and you could get a plastic plant saucer to fasten on top someway so that the pot sits firmly. I have several of those plant stands but no cat.

These are just poorly designed for a plant pot with soil, damp soil. Cat or no cat, they’re just itching to get knocked over, can only hacked a very small pot, trailing plant so as not to be top- heavy. And still have to be positioned by sone source of light.