The old school way of doing severe battle damage in Gunpla or toy repaints is melting the actual surface with soldering iron or a hot nail. This melting method produces beautiful and realistic results.
However, what if you do not want to actually melt the toy or model kit?
I highly recommend Green Stuff!
Yes you could use putty, epoxy putty, Tamiya epoxy putty or any putty or any material for that matter. I have used so many kinds and I have to say that Green Stuff is the most manageable.
Tamiya modeling putty comes the closest to Green Stuff when it comes to ease of use. Green Stuff though is less sticky and is a bit cheaper! Green stuff is not sandable though as it hardens like hard plastic rubber of some sort.
I will update this particular post once I have painted the Green Stuff battle damage effects. Hope you like this tutorial / tip post. Until next post guys! :)