You can actually make this tower as big or as small as you want, although I built it to seven feet. It is highly customizable, and uses as much or as little K'NEX as you have. If you make it, please comment and tell me if it worked out!
Step 1: The Base
First, build the base. It should be simple enough to follow the picture. Nothing is absolutely set in stone, and if you want to make a few small adjustments that's fine. However, try to keep the basic shape of the tower.
Step 2: The Rods
These will make the sides of the tower. You will notice that, in the picture, we have produced a rather haphazard collection. The actual rods are, in fact, not important in the grand scheme of things. What is important is that, somehow, you get eight rods of the same length. You can make bigger rods out of two smaller ones and that will work fine too.
Step 3: The First Storey
Connect the rods onto the base. It doesn't matter which ones go where, and it shouldn't be too hard to follow the picture. If there are any problems, please comment.
Step 4: The Base of the Second Storey
This may look a lot like the base of the actual tower, but don't be fooled! The tower base only has connectors sticking up. This one has connectors that both stick up and stick down. Look at the second photo. Apart from that it is the same. Again, if there are any problems understanding the photo, please comment.
Step 5: Rods Revisited
The first photo for this step shows more rods, introducing an idea which we call "rod connection". This basically means that some rods are connected to each other, instead of just connected to the base. This strengthens the tower. You don't have to connect rods, but it does help. The second photo shows how to connect the rods onto the second storey base.
Step 6: The Tower Takes Shape
The picture shows how to connect the two sections that you have built. Connect them.
Step 7: Higher and Higher
Repeat steps 4, 5, and 6 as many times as you want -- keep building story's and adding them on! You can build as many extra story's as you want. Not including the one that you've already built, we made seven. As you can see in the second photo, they're a bit ragtag. This is fine.
Step 8: The Top Floor
One last variant on the floor design. This time, only the four connectors in the small square at the back stick up. All of them, including the four connectors at the back, stick down. Don't connect this to the tower just yet.
Step 9: The Spire and Ornament
The spire is highly customizable. It's just a tall box, with each side the size of a blue rod. It can be as high as you want. Picture 2 shows the ornament. This has no purpose, it just looks cool. Picture 3 shows how to attach the ornament to the spire.
Step 10: Finishing Touches
The first picture for this step shows the top floor with the spire attached to it. The second shows how to attach the whole shebang to the tower. You're finished! We put some flags on after taking the pictures.
If the tower tilts, twists, or even falls over, just pick it up off the ground and put it back down. Doing that enough often has the desired effect.