When I was a kid Play Doh was king we played with it until it drove our parents crazy. It's not the easiest thing to remove from carpet, in fact I don't think I let my kids play with it just for that reason. Now kids have this amazing product: Plastimake

I must admit It's pretty cool...check it out:

There's another rival product I found on Amazon called Thermomorph... It must be a hot seller because every web site I checked it was sold out...I want some!