It's far easier to purchase it if you aren't hurting for the money or adhering to a budget.
With a 8' engine wiring harness kit from DIYautotune, and a couple of the end connectors (also sold there for cheap) there is more than enough wire to make the engine harness and the relay board cable. Just have to be extra careful making sure you solder the pins to the right place. The numbers on them are hard to read.
