Portable Gun Barrel Holder

Update 24Oct2018: The suction cup holders have been field tested with photos attached. I'll remove the work in process status. If using the suction cups to which I linked below, their "sticking" ability was unreliable in colder weather and/or dusty windows. We found that removing the plastic suction cup "backer thing" did the trick for those that wouldn't stick, even in times of driving over rough terrain.
Know your laws, practice safe firearm handling, at minimum, keep firearms unloaded w