Plunger Blowgun

I was watching a Mike Shake video, and he had the idea of powering a blowgun with one of these pneumatic plungers.

https://www.amazon.com/dp/B0DPKJC58B is the plunger I used, though I think the internals are mostly the same across most of these. Obviously the rail won't work on a different model, though.

https://www.printables.com/model/62497-picatinny-rail 

I remixed this rail to fit on my model. I have two 1/4" nubs on the bottom. Mark where it goes on the plunger by putting some paint on the bottom of them, drill it out with a 1/4" bit, and then I glued it on with epoxy. Super glue would probably work as well if that's what you prefer.

The main internal shaft was a bit too tall for my printer, so I made it two pieces with a coupler and epoxied those together.  

I can not for the life of me figure out why this is leaking air out of the barrel. I have been through several different versions, and I am still no closer to figuring it out, so I am calling this good enough. It leaks about 10 psi per 45 seconds. 

My blowgun is an old Cold Steel blowgun. The OD on it is 19mm, and I worry that it might have changed over the years. That might be something you want to check before printing. 

It is pretty easy to disassemble and reassemble. The thread on the main bolt, both factory and this model are standard right-hand thread, but it did throw me off for a bit because the orientation is from the pump side. You will still need the original O-ring and the bushing from the bottom. 

I am planning on cutting down my blowgun to about 28" in length, but it breaks my heart a bit to do that, so I haven't done it yet. It's pretty cumbersome with the full 4' barrel, and it's hard to pump since you can't brace it against the ground. That also means I haven't tested the pump stand yet. I am also thinking about making a version using 1/2" PVC pipe. I find 1/2" pipe fits the sharps pretty well but struggles with the thumpers. Since it has to be muzzle-loaded, you will want to use something for a ramrod, like a dowel rod.

I have been printing my parts out of CF PLA 60% infil. You may want to use PETG or ABS or something of that nature. I'm not an engineer, and this can pump up past 80 PSI. This hasn't blown up on me, and everything seems pretty solid, but please be cautious and use your own discretion.   

This thing is VERY powerful and is not a toy. Please be very careful with it. Do not point this at people or animals. Always load the dart BEFORE pumping. You may want to look into your local laws before printing this to know if something like this is legal to possess in your area.