I would use araldite rapid as it does not set quite so hard as the normal type so is not quite so burdensome if you want to fill a dent. i.e a little at a time and then sand back to a flat surface. The isopon stuff is quite brittle and needs a good "key", something like araldite needs rather less.
Like araldite? Or is anything that comes in two parts with a hardener an epoxy?
Was looking at Isopon P38 filler since you can get it in small packs.