Ehrm, I beg to differ. My 4 year old daughter has recently also started loving to draw. But, she pretty much refuses to let go of her masterpieces, at least we conviced her to store them in a shoebox, so they're not spread all over the house. And the pencils... Well, I've been picking up an awful lot of pencils from all over the house.

So I'm not sure I agree with the "lowest clean up time", even though I'm really glad she's picked this up as a "hobby".