Pinterest is full of puffy paint recipes. I twisted this a bit since my oldest is still a bit young to not eat paint.
In a bowl mix equalish parts cheap shaving foam and white glue (dollar store be my friend)
Then smear in random piles this on card stock and let dry on a flat surface for a day or two.
Turns out somewhat like a topography map.
Then give to toddler with their favorite non toxic paint and a brush or sponge.