Go to a scrub store and get some spiral plastic stethoscope wrap. Its like $5. It is made for single tube scopes but you should be able to make it work, it just may not go up all the way. It worked pretty well on my cardiology even though the tubing is a decent amount thicker than other scopes.
It is hard to tell since its black on black but I bet it will look way more professional than tape.
I got some because my tubing was getting really scuffed up and faded and leaving rub marks on my shirt. The harder plastic feels better hanging on your neck for 12 hours.