I always try and find 'plain' looking bags to hold most of my stuff when i can and 6 bucks for a ammo bag is not to bad. Wal-mart has some cheap tool boxes that i use to hold my ammo. Driving around with a vehicle full of "Craftsmans tools" is better than driving around with bags with "NRA" and "Smith and Wesson" on them.This may belong in another heading since I didn't build it.
I have been looking more and more into more discrete rifle bags, gym bags that kind of thing.