The Node Router is the weaver's needle that stitches your Routing Nodes into a coherent network. Its use is straightforward; hold sneak and right-click on one node, then do the same to another within 16 blocks. The two are now linked.
Right-click any other block to deselect. See the Routing Nodes entry for the full picture.
A slender wand of bound Spiritus. Unremarkable in appearance, indispensable in practice.