GRAVEL GRINDER WITH 2 TOY TRUCKS FOR CONSTRUCTION FUN: The gravel grinder, dump truck, and road roller construction vehicles include lots of fun ways to get creative with nontoxic Play-DOH compound. Boys and girls ages 3 and up will really dig these rigs! ROCK TUMBLIN GRAVEL GRINDER: Load some fresh Play-DOH compound into the gravel grinder and turn the handle to crush it into rocks. Kids will love watching the rocks tumble into the bed of the dump truck. Make a splash with the Dump Truck – it squeezes with movement and laughter. Squeeze Play-Doh debris from the bed of the dump truck, then roll the truck along the Play-Doh compound to print tire tracks.