Let toddlers finger paint inside a wading pool
Before you fill the kiddie pool with water, here's another idea, from Isabel:
My kid likes to paint himself and any nearby surface during finger painting (he's two). Indoor finger painting in the wading pool makes clean-up easy. I put the pool in a different room during my kid's post-painting bath. Then I just put the pool in the tub, rinse it out and leave it in there to dry upside down.
I'm just impressed that you let your two year-old finger paint at ALL. Good for you -- I regret thinking it was "too inconvenient" when my kids were little. Missed out on some priceless moments for all of us.
You could also use a kid's wading pool as the basis for a "sensory lab" filled with dried beans, rice, fluffy stuffed animals...that would be fun for a kid way past the toddler years! My nine year old would love that!
PS. I'll bet you've got a neighbor who's dying to get rid of their old kiddie pool. Ask around or Freecycle before you buy a new one.
Related: Turn a baby bathtub into a ball pit