I've been making some form of a K'Nex Christmas tree since high school. As I collected more pieces, I started making it taller. It's right around 48" now. The tree requires a lot of pieces. Some of my design choices are made because I don't have as many specific types of pieces as I would like.
Step 1: The Base
Step 2: The Trunk
With most of the pictures I'm showing you one of the four sides of the tree.
Step 3: The Corner Branches
The corner branches are largely what help keep the tree balanced. You will need four of the corner branches (I only show one in some of the pictures).
Step 4: The Branches
These bring the tree to life. If I had more pieces, I would make the bottom level branches simpler.
Step 5: The Star
No Christmas tree is complete without the topper. I'm using a star here.I