According to reviews, your new friends can stay fresh and squishable up to three days out of water and can retain their shape in water for about a week.
The kit comes with magic gel, molds, gloves, a scooper, and magic powder to get things started.
Promising review: “These were so cool! And such a good value for your money! They were so easy to make, they take maybe three minutes to make one to put in the water to form — we sat for over an hour last night making them! My son and I both had a great time. They are firm once formed, so they can easily be played with! We truly loved this find!” —Maddie
Get it from Amazon for $25.99+ (available in three styles).