pic: T-Shirt Cannon Bot Concept WIP

[Steven Smith]

Could you, for instance, combine 4 1/4" feeds and get the equivalent to a single 1" feed?

Flow rate is proportional to the area, not diameter. Also, tubing is generally specified via the OD not the ID, so a 1/4" tubing might be closer to ~1/8" ID depending on the wall thickness you have.

Finally, tee fittings have a pretty significant pressure drop (relatively speaking). When you are discharging air in a cannon, your air flow speed is likely going to be quite high, so having a significant number of tees might be an issue. If they were between your high pressure tank and your accumulator, it wouldn't be an issue, but everything that is "firing" when that valve opens needs to be relatively large with minimal pressure drop.