Mod Roc. Bumper classpack for even better value! A fine gauze material impregnated with quick drying plaster. Simply dip into water, wrap and shape - it will set like rock. 3D models can easily be made by applying the 'Mod Roc' onto mesh. Roll size 15cm x 2.75m. Age 5+. And buy this Mod Roc Pack of 4 Rolls Now £3.99.