to make a functional node, you would need an rgbled, a capacitor, 4 resistors, a pcb, and the chip. (the actual node also contains 2 diodes)
if you're making something similar to the regular smart string node, you might as well just get the smart string node. they're fairly inexpensive, and hard to match quality and price -wise.
plus, the time it takes you to build one would be at least an hour (after you got the hang on it.,so a string of 128 nodes, would take awhile to make.)
the only reason why i did mine, was that i didn't want to use individual light control with putting flex strip inside pvc for my arches.