This design stars 3d printed parts. The printed components are designed to fit together pretty closely. They also hug the circuitry pretty tightly. Depending on your printer, infill, material, astrological sign, etc. you may have to file off a little here and there to get everything to snap together. Hopefully the tolerances designed into the components will be enough to equal smooth sailing.
The ring is built like a sandwich, with all the components mounting into the ring body layer by layer except for the cast crystals, which get pushed up into a retaining chanel in the ring cap. To manage wires, you'll want to do a test of the whole circuit with wires that are a little long and then trim them to length and re-solder once you have a sense for where everything should fit.
Here is how you hook up the electronics that power the ring. If you get confused during assembly, refer back to this diagram. If you're new to electronics, it helps to assemble and program everything leaving the wires long so you can easily resolder and troubleshoot. When you get an understanding of the design and where things fit in the ring, trim the wire down for the final assembly.