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).