Nice cable!! Where did you get the split from ?
Everything you see aside from the heat shrink was from Cosmic Cables in the UK. That Y-Splitter is the Viablue small seen in this link. Should be easy to find in the US too.
However, it's worth pointing out that it's actually just got a solid bore without two holes at the top. I chose it because the cable is kinda chunky, but the larger splitters were just too big and bulky, so this was a better solution for me. What I then did was use heat shrink on the core 8 wire, plus two smaller bits of heat shrink around each 4-wire split (left/right), all of which is hidden by the splitter. It wasn't absolutely necessary to use the heat shrink on the left and right once I'd finished the braiding, but I just wanted to keep things solid and neat, but it would work perfectly well with just the main core wrapped in shrink.