OK so for about 30 dollars and ~2 hours, you can have your own super accurate butane powered air soft gun, wrist mounted shooting at 1600fps. Its an attachment to the hidden blade and it can also be used by itself.

Youtube is having troubles with the audio =(

Step 1: Materials and Tools!!!

All of the parts were avb. at my local hardware store
You'll need

1 Male NPT quick release
1 Female npt valve
1 9/32 brass pipe (No Bigger or smaller!!!)
13/32 brass pipe (adapts and fit to most standard butane bottles, check to make sure ti fits first)
1 butane bottle
plastic bb's
metal putty!
5/16's cork
light load 1/4 od spring
1/4 npt to 1/4 inch hose barb
2 feet of 1/4 teflon hose ( I used some low pressure, clear teflon i had lying around)

Hot glue
Dremel!!!
Cresent wrench

Step 2: Pipes

Using a pipe cutter cut 3 inches off your small pipe
then cut 2 inches off your big pipe

Good? good.

Step 3: Its Hamm----dremel Time!

Take your dremel and widen the ends of the brass pipe with a light sanding bit in you dremel (The pipe cutter shortens the ID near the cut)

Now take a cutting bit and cut off 6/16's of an inch of pipe through 1/2 of the pipe depth about 2 inches from either end of your big pipe.

Now use you dremel to flare the end of th 2*9/32's pipe and stick the flared and into your new cut on the big pipe, Which the putty and cement it into place there.

now us your dremel to open the inside of the MALE npt up a bit, mix more putty and rub it onto the base of the long pipe, now stick that into the male npt. It should be a snug fit.

Step 4: Hot Glue Hurts on the Skin =(((

OK CAREFULLY take your hot glue gun and lue the NPT valves quick release trier open

thats basically it....

Step 5: Pipe!

Attach your 1/4 npt to 1/4 hose barb onto your npt valve and slip you hose on, then, tighten with a hose barb

On the other end of the hose put hot glue on your smallest pipe, squeeze it in and fasten with a hose barb, your ready for a pressure test.

Put the bottle on the small end of the hose and squeese straight in, if you see liquid in the tub, your good, now carefully take the hose off (Butane will spray out, be careful its -170C!)

Step 6: Your Almost Ready!

Glue the cork to the spring and your done!!!!

Step 7: Final Project!

Its shoots at 1600 fps! its stupid fast! and dangerous BE CAREFUL!

the math 13*.012 = .156 * .2 = .0312 *54125 = 1598 fps
(sheets of paper) 13
(Densile grams per 1/4 inch) .012
(gram weight per bb) .20 grams
constant of paper-fps conversion) 54125

Holy crap thats hard math, basically we have the amount of paper per 1/4 inch we punch through * the gram mass of the bb * a constant value that equates in velocity

Step 8: Saftey

I am not responsible for your actions, this is a very dangerous project utilizing high pressure, super chilled gases and high velocity objects, try it at your own risk.