The pressure we're using is relatively low so I don't think too much pressure would be an issue. Thanks for all of the feedback though; I'll look into the stopper idea for the time being as that seems to be the cheapest and simplest.
Does drilling through rubber work fine with regular drill bits? I've never done it and I would just be worried about ripping them apart if I tried haha
Here's a brief overview of our current setup (for a school project). We have a CO2 tank with regulator connected to 6 2-liter bottles. Currently we have drilled two holes in the top of the 2-liter caps, one for air in, and another for liquid out. We are controlling the flow out by electric...