Something as simple as playing with store bought play dough can allow your child to be creative but takes nothing as far as prep time :)
[We made homemade Oatmeal Play dough awhile back if you want to make your own!!!]
We had a friend join us today to play!!
While they were discovering on their own I interjected with things like "What color(s) are you playing with?". Store bought play dough is great when you don't have the extra few minutes to create your own but still gives your child the quality time they need from you!!