The author remixed this model.
I really liked the original design. A lot simpler than other's I've seen. I purchased a Liouhoum soldering iron and it didn't fit in the supplied arms. I shortened the clamp. I'm also including a link to the linear rail I purchased.
I used M3 12mm cap screws with a nut to attach the spring to the assembly. The nut is tightened agains the body, leaving space for the spring to easily flex, keeping the screw from loosening.
Note: I'm not including the unmodified parts. You should head back to BaGooN's original model.