I have bneen researching fiberglassing techniques recently. Some people, mostly imprort tuners and such, use kevlar to make a wrap over a part or dash piece then cover with epoxy resin so its nice and smooth looking....same tech as carbon fiber wraps..
I looked into the kevlar and its made by kevlar people but its not the same type material as bullut proof stuff, but you can probably source the bullet prooof stuff if you contact the manufacturer from thier website...least thats how it looked to me.
not sure if it would work or not, but kevlar wrapped bus walls might be what your looking for...big $$$ though I bet.
What about flame throwers
like on the jaquzui bus only turret mounted for added saftey put servo motors and a cam on the turret and wire it to a control box or radio control box so you can use it from hiding.....btw I would really like to see how he made that thrower.
I personally dont planned to be armed with guns when I go full time, we wont be able to buy ammo for them much longer anyway. I have a very nice overbuilt spear gun which I can hang on the wall next to the picture of the "record sized fish"
Stun batons are a nice choice for hand to hand situations...take a 2-3 day course in some form of stick fighting martial arts and you can be very very effective. I could beat down a bear with one, with the neat side effect of watching it piss itself and flop and twitch.
Over built paintball guns are interesting devices, I have entertained the idea of cast aluminum balls. however a rubber paint ball (they use them on courses sometimes and u can ebay them) fuckin hurt and rubber bullets from tactile shotguns can drop a full grown crazie and make him go night night...google used to have plans for alternative paintball guns, like gatlin guns and such.
Bus with air brakes/ or air tank could be built to produce enough psi air for some very interesting weapons, but youd need to build em yourself to get anywhere near enough force...but again probably very cheap easy compared to other more traditional methods....but traditional methods of self defense will be the first to become exticnt, hell already waiting lines for ammo, only getting worse.
I know I am rambiming but good old fashioned potato cannons, filled with your choice of "ammo", I like the idea of small nails and broken glass or home built "firecrackers heh". and flare guns. with minimum effort you could turn the sky into your own personal 4th of july raining burning puncturing pain onto those below.
napalm is easy to make as well.
My thoughts are your weapons should easily not look like weapons when crossing border patrols between states(yeah I know not a issue yet) and yet be quickly and easily usable to defend.
I once saw a fight break out on a construction site...a Air nail gun was used by one guy to shoot the other guy full of nails..turned him into hamburger before he was stopped.
to many situations where having a gun on my person could = detainment or harasment from the man...a box of air tools, paintball equipment, fishing spears etc would pass with little more than a raised eyebrow.
NEver understemate to power of light, a lot of very very high powered lights can make your opponents blind and its hard to hit what you cant see..enought time to drive away mabey...thats why police use huge spotlights at night blocks...you cant see how many there are or where they are.
10 billion ways to kill a man and the gun is quickly becoming more trouble than its worth.