I will show you how to build a camera dolly out of K'NEX.
Step 1: Let Us Build First Leaf
In the picture you can see the necessary K'NEX parts for the first leaf. Connect the parts as you can see from the pictures. You need to build 3 leafs.
Step 2: It Is Time for Tires
In the picture you can see the necessary K'NEX parts. Connect them accordingly to picture.Do not clinch them too much. You should build three of them.
Step 3: Connect Tires and Leafs
You should connect each leaf with each tire by using the parts from the picture.
Step 4: Fix Two Leaf Into Each Other
By using two white parts you should connect two of the leafs into each other.
Step 5: What About Third Leaf
For the third leaf, you should add two white parts into it. as you can see from the picture. But do not connect it into others yet. Because this leaf will be moveable.
Step 6: Connect All
By using the yellow rod connect all leafs into each other. Two of them will be fixed and third one will be moveable. See the pictures.
Step 7: It Is Finished. Put Your Tripod on Top of It.
You can arrange leafs according to your tripod. Put it and move your dolly :)