You can put a bell around their neck, which apparently reduces their catch by half[1]. The cats usually don't look happy about it though.

[1] https://www.publish.csiro.au/wr/WR09127

You need to be very careful with the string/lace/collar you use to attach the bell, it should be strong enough to resist casual attempts to remove it, but not strong enough to not break when some substantial force is exerted on it (weight of the animal).

Single point anecdata, but I once found a cat with a collar that remained stuck in a fence, the cat - attempting to get it off - managed to insert a leg inside the collar and that - with more attempts to get free - made a really deep cut under the armpit, the poor cat was half choked and it took weeks for the wound to heal. .

Maybe people should not let their house cats out, right? We can call the crazy cat lady "crazy" but she wouldn't let her babies out, let's all be more like crazy cat lady.

Please make sure to use a breakaway collar, or the cat could get stuck and die because of it.

I did that to a cat once. Poor thing didn't like it, and started backing up, fast. We were indoors, but it still took several minutes to catch her to take it off. I've learned my lesson and won't try that again.

We belled or cat, she got used to it, completely stopped her catching birds

If nothing else, it’ll be hilarious.

(I’m kidding, don’t put paint on your cats people. You can dye them safely though! Edit: safely for them, you might get hurt)

It's hard enough to get them to hold still on a flatbed scanner -- painting would be a team effort.