How to make the Nova
(model name: MS-SSAL)
Here is what you basically need. A wooden dowel, some leather (felt would work too), a handle for the plunger (keyring shown), a stopper (marker cap shown), small extension springs (easy to pull back, the ones I got was model # C-207), a hole starter, a hole threader, a 1/2" pvc cap, a 1/2" pvc T connector, some 1/2" pvc, and a barrel to fit your ammo (the ammo I used was 3/8" foam caulk saver, so I used a tube that the dart can fit snugly inside)
You will need to cut your 1/2" pvc into 3 parts, an air chamber (sounds complex, but its just a tube bigger than the barrel):
The air chamber should be pretty long. The longer you make it, the more power it will have (unless you make it WAY too long, then it won't shoot at all. I suggest a foot or less).
A small nub thingy for the back of the T connector:
This small piece of PVC is just to stabilize the plunger. Nothing too complicated, just cut a piece about the length of one and one half of an inch.
You can make this any size you are comfortable with.
Assemble your PVC parts. It should look something like this. See the air chamber in the front, the handle on bottom, and the nub thing at the back.
The wooden dowel:
Just cut it so its about the same size of the air chamber.
This is pretty important. Its what you grab to pull back and what keeps the plunger from snapping every time you shoot. The stopper should be larger than the PVC (in width, not length). Try using something simple, like a marker cap for instance. It has a hole in it (to glue to dowel in) and its soft enough to piece for putting a key ring in.
Now, attach the dowel to the stopper via hot glue or epoxy. Fill the stopper with glue to enforce it.
Sorry, the picture for this step didn't turn out. The leather. The leather piece should be about 1 millimeter wider than the inner diameter of the PVC. Get the hole starter and gently make a small hole in the front of the dowel. Use the hole threader to thread the hole. Fit a screw inside of it to see if it works. Pull the screw out. Get the hole starter (just a pointy thing) and make a hole in the middle of the leather circle. Screw the leather onto the dowel. Viola, your plunger is done. Now, you have to lubricate it. A lot of people use WD-40, but I don't. It dries up. I would use motor oil or bicycle oil. Whatever you do, don't put too much on. Just dab a little on the edges of the leather and put it inside your gun. Push the plunger back and forth a few times to make it slide smoother.
Sorry, the pic didn't come out for this one too. Just get the barrel that fits the 3/8" foam backer rod SNUGLY (meaning if you fling it around, it won't budge, but its easy to push out) and hot glue it to the inside the of 1/2" PVC air chamber, and make sure it doesn't hit the end of the plunger.
Just use good old duct tape to put these on. Tape one end to the stopper and the other about mid-way of the air chamber (the further you put it, the more power it will have, but more difficulty to pull it back and to attach the springs). Once they are on, use a hot glue gun to try and seal it better. Make sure these will **NOT** come off. If you are really good at this kind of stuff (and know what I'm talkin' about), you can try putting a hose clamp on like mine.
Congrats! You have completed the NOVA. Try testing it out. I got 50+ feet with mine. Try building your own now, with different PVC sizes (or CPVC) and try adding in features, like a clip, or a trigger.