InkJet

I'm not sure what kind of pressure you're planning on running this at, but I'd assume you'd need a decently large solenoid and battery to push against the pressure of the spring/air pressure in your little actuator valve, which might be a limiting factor, just sheer size.

That is very very nice. Great first post!! Did you do this on a basic mill and lathe, or CNC? Because I own a regular mill and lathe, and might try to do that.

And i have to vouche for the spray silicone lube, i got a can of it for my airsoft guns a while back, and whenever i do a mod, i spray a bunch down into the valve/pump tube/plunger tube, and it seems to help the performance/effectiveness. That can hasn't run out yet either.

Do you have a catch on the metal where each barrel is? I see little divots in the metal, but all there seems to be on the metal piece attached to the NF is screws coming in. What is the adhesive looking substance near the bottom of the barrels? Didn't mean to interrogate you there, just curious, it's an extremely ingenious design, great job!!!

I would say that .25s may or may not be good enough, depending on what the darts are being shot out of. If it's out of a maverick, they should be fine, it it's out of a BBB/AT2k, i would say no. If you've got someone over 18 to get you airsoft BBs, just go to walmart and get slingshot weights. If you don't have the over 18 person, go the more expensive route, fishing weights.

Well actually, if you got your FBR at ACE, they're FBR is very thin. I got some from their just to experiment, and for me, without any heating, the foam fits almost loosely into CPVC. You could try getting foam from home depot or some other hardware store.

Well, of course you can replace it. The only problem with that is that the maverick uses a very small flimsy piece of plastic to pull back the plunger. It is what the silver colored rod pushes back on. If the spring is too powerful, the plastic will simply snap off, making the maverick useless. The first gun i tried to mod was a maverick, and i tried to stretch the spring. This led to after about 50 shots, the snapping of this piece. If you found a way to reinforce it, it may work, but i don't see any way really...