Take one of the short wooden dowels and two of the longer ones.
Put the 2mm drill bit into your drill. Drill a pilot hole from the top of these dowels(the shaved side). Make sure to center it, and keep it straight.
Drill another pilot hole from the bottom of each dowel.
Change drill-bit to the 6mm one.
Now, go gently. You'll want to drill as far as you can into all sides of the long sticks. If you don't center the drill in the wood, you'll crack the dowel.
Make sure there's a clear path through the short drill.
Open a hole into the bottom of the drilled path, through each long dowel.
You now have a gorgeous cable system