Used polymorph a lot in the past but it sometimes does not hold on the grip, feels slimy in the summer is not much fun to grind down and alter, very small window of moulding opportunity as it can cool rapidly, is quite heavy if a lot is used but is firmer and does not squidge out as some polyester filler can but I like that easy flowing property myself. Try it you may like it but I no longer use it in this context.