Cornflour and water does that in the right proportions..

Mix it correctly and pour it out on a surface and you can move it round with your finger, but if you bang it with a hammer, instead of splashing all over the place, it hardens and compacts without splashing around.

^^^ Courtesy: "Why Don't You Go Out And Do Something Less Boring Instead" BBC1 circa 1987

Posted By: Arizona Bay, Mar 3, 10:35:12