Non-lethal traps like what he's proposing are legal and surprisingly commonplace. A ton of banks have dye packs hidden inside wads of cash that explode after a bank robber makes off with the money. There's also anti-vandal paint that coats the hands of anyone trying to climb it with a slippery greasy paint.

Even the popular myth that a fire alarm pull station will stain your hands with ink is based on an actual product. High schools with a string of false alarms will sometimes put a marking compound on the handle that is indelible and changes to a bright color when someone tries to wash it off their hands.

Spraying a thief with fart spray and glitter is not illegal.

Booby traps are illegal if designed to cause bodily harm. It's not so cut-and-dry when it's something merely annoying, like a glitter bomb, though I would definitely not want to be the manufacturer trying to defend that in court.

Pepper spray, whose purpose is to cause bodily harm, was included in the list of ingredients, so the described booby trap would, indeed, be a prohibited “intended to cause bodily harm” one. (Actually, not only do the general laws on booby traps come into play, but using pepper spray other than in immediate self-defense in California is a crime.)

I realize that. That's why I said "annoying", not "less-than-lethal", and used glitter as an example.

Hm, okay, so let's take the pepper spray out then. Ink, honey, feathers, flour, glitter, fart spray.

Any that would cause bodily harm, or be argued to cause it, definitely.

The fart spray and glitter bomb, would be interesting to see how it would be interpreted. I wouldn’t want to be the test case for it!

Why would this be a trap? They're free to run, they will just look like a glittering sticky chicken and smell like shit.