Cheers mate.
Easy enough. mixture of broken up cork tile and wine corks super glued down. Then using a precision superglue applicator get some superglue in the cracks and on the flat areas (will be plenty due to the cork tile) and get some mud on there. When I say mud....get some sort of metal container, go out into your back garden, scoop up some earth in the back graden and then put the container on the radiator/somewhere hot let is dry out, result - you have some of the finest basing material available, loads of lovely textures. One tip make sure there are no earthworms in the soil, not very nice to fry an earthworm on the radiator, after all you just stole HIS house....