Any ideas on how to change the physical appearance of a Nerf gun?

My friends and I are getting into the whole Nerf moding thing and I want to change the appearance rather than the distance it can shoot.
I was thinking Bondo, but I don’t know if it will stick to plastic. I thought about paper mache, but I’m not sure if it will withstand the bashing I’ll probably give it.
My arts & Crafts skills are next to nil but I’m willing to try just about anything.
Alright, my Flutheramaknickknacks….Go.