Hang a unicorn or rainbow piñata that's filled with small toys and candy. Order an arch of rainbow-colored balloons from a balloon business or make one yourself using a balloon arch kit. Display it over the food table or place it near your front door so the guests must walk under it to enter the kitty party. Purchase a bubble-making machine and let it run throughout the party so soap bubbles constantly float around the party guests. Cover chairs with organza slipcovers, which you can purchase or make yourself. Make many artificial castles and place them at different places in your kitty party room. Hang tissue-paper pompoms from the ceiling.