Well, see what we have here.
It shoots far and you can make it in 5 seconds.
a normal clicking pen
2 springs.( you can get them from other pens.)
thats all you need.
Disassemble the pen. You'll have an ink cartridge, a spring, a pressing thing and a cylinder with a circle on top. Also the two parts of the housing.
Once everything is separated, put two of the springs on that cylinder thing.
Put the spring that was already in the pen on the front of the ink cartridge.
Now put the pressing thing in the bottom part of the pen.
Put the cylinder thing in the bottom part of the pen with small side down.
Put the ink cartridge with the spring in and screw on the top.
Uscrew the top part of the pen until you know its gonna come of.
Now press the thing poking out at the back and your awesome pen gun will shoot.