2-part polyurethane expanded foam?

That's basically what ELSO (or is it ESLO?) and Ziterdes make their products out of and it works ok for terrain.. and at the smaller cell size even some scenery.

You need to cover it with something to fill in the surface holes mind you - not a problem for terrain usually. One of the tricks to it is to ensure that it does in fact bubble over the required fill area - ideally use a Perspex (or similar) cover to the pancake mould with a hole in it to let out the expanded foam. The upper areas of the expanded foam are always much larger than the lower areas.. so the lower areas which form the surface of the model (lets say) are ok to work with and the biggest bubbles come out of the top and you slice off.

Anyway - we're not massively impressed with it although it does have its uses as lightweight space filler under terrain surfaces. Judging by quality Ziterdes et al have a premier version or a better methodology for *casting* as the cell size in their products is much smaller.

The expanding foam is also vicious on mould materials, especially anything rubber based and even silicone without liberal amounts of mould release...and I mean *Vicious*.

The stuff we use sounds a little different though as its almost rock hard and you could have half a game of cricket with it.. well, a 20-20 match maybe... so maybe the alternative product as you suggest is better (sorry cant help on experience due to product differences.. we use this stuff rigid foam
rather than the american smooth-on products (only due to lack of easy availability mind you).

Should work ideally for island for POTSM etc though.
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