How can I make a custom Gibs model for a entity func_breakable?

[lavasap13]

I'm trying to make a func_breakable to stop throwing rocks when it gets destroyed, but for some reason when I set material type to none it keeps on doing it. So the only solution I can think of is to make a custom one but I don't know how to add it. I can model it in blender and create the .mdl file but past this point I don't know what to do.