looking at the sites there looks like there is a big diffrence in the RTV shore hardness from 15 - 27 is it best to go for the 27 ?
im sure i bought from Eastcoast fiberglass for there RTV and resin and there resin seemed a bit rubbish / brittle
Could someone also describe the diffrence between Polyester Resin and Polyurethane resin eg advantages and bad point
Well, for prop purposes, unless you're making something huuuuge like a Proton Pack and need the extra strength afforded by fiberglass-inlay, stay far away from polyester because it stinks like hell. Polyurethane can be poured (in smaller quantities) in a well-ventilated hobby room. (Some do give off less-than-healthy fumes though- even if they are odorless, so use a mask anyway and keep it well ventilated!)