I simply spray painted it black, added some strategic caution tape (of course), a few warning labels, and a no ghost logo on each side.
I lucked out in that my proton pack fits inside the case perfectly.
Next week I plan on making another one, complete with foam that has cutouts for all the other gear (thrower, belt gizmo, ecto goggles, PKE meter, etc). That way when I go somewhere, I can just bring it all with me in two cases, rather than a random cardboard box.
My scratch built Gizmo - http://www.gbfans.com/community/viewtop ... =4&t=37121
My scratch built Proton Pack - http://www.gbfans.com/community/viewtop ... =2&t=36757