Here she is, the keychain coax. I think it goes without saying that I didn't build this for performance seeing as how the barrel is only about one inch long. I do think that it is a cool novelty and I also think that I have the coolest keychain on the planet.
I have test fired it at around 100 PSI so far and it works. It will shoot a small nail dart across the room no problem at this pressure. I will wait till tomorrow to test it at higher pressures (wanna be sure the epoxy is set up). If I can enter a soda can, I will be impressed and satisfied.
Here are a few pics....


The business end


Compared to my pengun...

The nail darts are tiny...

Not at all to scale, but I hope this is somewhat clear....

The up(down?)grade:

It entered AND exited a beer can! it only took 400 psi


The nail darts stick into drywall about 1/4 inch at 400 psi

DAMAGE video... Sorta. Me shooting a beer can at 400 psi
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