Many bottle rockets across the web are amazing, but are amazingly hard to build. I wanted a rocket that looked good in the air but was easy and not time-consuming to build. This particular bottle rocket is a hybrid of many different types I found, and though it doesn't go anywhere near, say 50 feet, to less competitive and easily impressed people, like my little brothers and me, it is pretty cool.

*Sorry for the grainy pics.

Step 1: Materials

*not all materials in pic

1. An average 2 Liter soda bottle
2. scotch tape
3. clear packing tape
4. an air pump
5. an average BIC pen, open on both ends (it'll have to fit in the pump, so one with a narrow end may be better.)
6. 2 straws (bendy or not, doesn't matter)
7. glue (hot glue preferred)
8. some poster boards (for the fins & nose)
9. A long, thin k'nex rod (recommended but optional)
10. a launcher, such as a cardboard box or a mediumish styrofoam cup

Step 2: Making the Plug

Wrap tape around the middle of the BIC pen until it plugs up the opening of the bottle tightly.

Take 2 straws and coat about an inch from the bottom with glue. Insert them together into the end of the pen valve that will go in the bottle and make sure they are glued. Let it dry.
This is to make no water go in the pen valve, and then into the pump.

Step 3: Fins

Draw fins on the poster board and cut them out. I made four, because it's easier to make it symmetrical and straight but you can make as many as you want. the shape could be whatever you want, too, as long as it's aerodynamic.
Of course, you can color them if you want...

Step 4: Waterproofing the Fins

To make the fins waterproof and longer-lasting, just laminate them with packing tape and at the end, cut the excess off the edges.

Step 5: Taping Fins to Body

Look at the pics; I taped yarn around the bottle to make sure the fins were straight. You can find some other method of keeping them straight, though.
Anyways, just connect a piece of packing tape (as long as the side of the fin) from the fin to the bottle. Then, make it straight and tape the other side.

Repeat for the other fins.

Step 6: Making the Nose Cone

To make a nose cone for the rocket, just cut out a big circle about 17 or 18 inches in diameter. (It doesn't have to be perfect.) Then, lightly fold it in fourths. Cut out one fourth of the circle. Wrap the 3/4th circle around itself and tape when it looks like a cone. (The edges should lightly overlap)

Step 7: Optional: K'nex Antenna

*If you're not using the k'nex rod, just tape the cone to the bottom end of the bottle and make sure it is completely straight.

The K'nex antenna serves three purposes:
1-allows you to shift around the nose cone to get it to be straight
2-reduces impact if nose cone hits ground so the cone won't be destroyed
3-allows you to center the nose cone

Okay, to make it just tape the k'nex rod to the center of the rocket's bottom where you'll be attaching the cone. Be generous with the tape and make sure it's secure.
Then, cut a hole in the tip of the nose cone only big enough to let the k'nex rod squeeze through. Push the cone onto the k'nex rod and tape at the tip.

From there, you can adjust it to make it straight, and it shouldn't fall off.

Step 8: 3...2...1...

It's time to get ready to take off. Fill the rocket about 1/4th full with water. Plug it up with your pen/plug
Place it on/in your launcher, which could be a box or something. I used a mediumish styrofoam cup that was open on both ends and put the pumper tube through one end and the bottle on the other end.
Insert the pen/plug into the pumper. Latch it closed and pump.