My opinion is that if it's just for fun, play around. spankings, wooden spoon, brushes, etc are basic around the house implements, but punishments don't all have to me physical, especially when it's just for play.
maybe a punishment would be writing "kitten will not be a bad girl again" 100x, OR she must polish your shoes to your 'satisfaction'...there are so many possibilities, just be creative!
my favorite play punishment reads like a rape fantasy (cuz I just like it that way). perhaps i was asked to be waiting for him naked in the waiting position when he got home, but I was too busy getting dinner ready, I wasn't in my place.....and then master shows me my place *winkwink*.
also, ask her what she likes. if she likes spankings because they get her hot, then that might be a good 'Play Punishment'.
Good luck to you & your kitten,
~ openlyrefined