Polystyrene wanted

Small safety point...many years ago I set out to create a stone wall using chunks of polystyrene stuck on a sheet of board. Roughly hacked into stone like shapes bits were duly stuck on board in wall pattern, it was meant to look like a weathered drystone wall you understand. Roughly hacked poly needed to be rounded, no sharp edges (well, very few) on a drystone wall. Some bright spark suggested applying meths with a paint brush to the edges to melt the poly, thus rounding the edges. Lovely, except you need a lot of ventilation when using meths this way. Apparently I finished the wall but spent some time talking to the fairies who were wondering what I was doing to their wall.... hmmm, lesson learned. It looked fab once I'd recovered and painted it all with shades of grey and mossy bits, very realistic, but was it worth the price? If you want smooth or weathered tombstones do any melting outside...and wear a mask even if you are outside too, just in case. Scottish pixies are nasty!! Rapunzel "Life is too short to stuff a mushroom"