terrorist threes

my 3 yo pushes my buttons every night, and she shares a room with her 6 yo sister. two nights ago i took away all her stuffed animals and asked her to go to sleep. she cried, then was playing again in a few minutes. then i went in and took her pillow. i told her if i had to come back in, her mattress was next. it was nuts, but it worked. for now. at one point a while back, i resorted to spanking her - i was at my wit's end. i was disappointed to find it didn't really phase her, so then i felt guilty for striking my child. grrr. sometimes you can't win - i was hoping to just startle her and help her hear me. that's not helping her, nor me.