Object permanence is the understanding that whether an object can be sensed has no effect on whether it continues to exist. This is a fundamental concept studied in the field of developmental psychology. You can read more about it here: https://en.wikipedia.org/wiki/Object_permanence

This infant toy is pattered after the Montessori Object Permanence toy. The little kid sits next to the toy and picks up the ball then drops it in the hole. Kids at the right stage in development are thrilled with this toy and do it many times in a row. Apparently their brains need the repetition to learn what is going on.

You don't need supports to print this toy. The lid snaps in place and holds tight. You might need to push sideways on 2 of the hooks when you snap it in place because it's a tight fit.

Version 1 square (this page)
Version 2 rounded
Version 3 tall spiral
Version 4 taller spiral with slot window