hey sstp,
I have a simple small metal lockbox that my carry gun and wallet keys etc will fit in. usually these lockboxes have mounting holes in them that you can run a small length of wire cable through. my cable is about 30", run it through the holes then make your loops and use the connectors (cable furrels I think they are called) anyway the ones you have to hammer to make the loop. then when you have to leave your gun in your vehicle you can run the cable around your seat hardware lock the cable and push the lockbox under the seat.
v-fib
and welcome to the highroad!