My three year old is really into building water fountain type things in the sink with cups and kitchen utensils. I'm having trouble finding a kind of toy like this to challenge him, and I don't want him running water from the tap all the time. And he hogs the sink when I'm trying to wash dishes and gets really upset when I disturb his projects. I did a google search and all I come up with are pool toys and bath toys. Are there any toys that are like those marble tracks you have to build, but use water instead of marbles? He is extremely advanced with his engineering skills and would probably like something designed for about age 7 to 10.