Gym Birthday Party Game Ideas!

I’m needing some ideas for activities we can do for our 3yr old daughter’s birthday next month. There will be kids ranging from 3-9 coming to the party and it is a princess theme, although some of the kids coming will be boys. My daughter just loves princesses. Anyways, it’s at a gym and we are planning on having a craft table set up and we will also have some balls and balloons laying around for them to do plus corn hole. I’m looking for ideas to do an o stable course without having to spend much money on it or some other activity we can do to keep the kids busy. Thanks!