At the hardware store, test different gauges/weights of electrical wire to see which will bend the easiest while still holding a shape.
Then, when you get home, make bubble wands by cutting lengths of the electrical wire with your wire cutters and bending them into squares, circles, or other shapes, making sure to leave a length to serve as a handle.
Also, make sure the ends aren't sharp!
Finally, if you're making your own bubble solution, prepare it ahead of time.
At the Party:
Fill a wading pool one-inch deep with bubble solution.
Let your guests dip the electrical-wire bubble wands in the bubble solution, then pull them through the air to make interesting-shaped bubbles.
Dip the hula hoop into the bubble solution, too, and pull it slowly upward to create a bubble cylinder.
If you find a willing participant, have him or her stand inside the hula hoop and form a bubble around a person!