Honestly I've painted nerf guns and added to them for steampunk gear, so props for cosplay/LARP/all the things like that. It works. Especially for some of my friends who have the mad painting skills from painting DnD or other tabletop figures.
Here's a gun I did for a steampunk look I did. First photo is the painting and adding the two tubes.
The 2nd here we added little LED lights that would light the gun up when I pulled the trigger, then added the 3rd little tube in the back, the water. The front was gonna have a needle so that it looked like an injection gun. I was going for a mad scientist apothecary type look.