Um, what size of rounds are these firing?
Based on that video, where you never see the gun itself firing, the garage door appears to be the old wood structure ones. So if thats a 2x4 and you have a spread from the paintball to coat it, I am assuming you are NOT firing 6mm paintball, the spread appears more like the normal 25mm that a CT gun would use.
Also, those guns that you have posted up look like solid plastic shells;, meaning that you'd have to bi-sect them to hollow them out, otherwise it appears that the magazines will not be separate from the gun.
"The hydrogen economy car from the people who brought you the 'Hindenburg
'" - Glen Foster
Condoms do not guarantee safe sex any more. A friend of mine wore one and was shot by the woman's husband!