I was not going to include the “Cummerbund” in this guide since it’s purely a rent only item (although you could buy it, but why?) Furthermore, it reminds me of my grade school choir where we were made to wear bright royal blue cummerbunds for performances.
But then, I discovered that it originated from India and was adopted by the British. How it was able to transfer from ultilitarian usage to formal attire is beyond me and my simple theories. The indians used it as a way to carry small items around their waist. The British decided it could be used as a way to catch bread crumbs at a formal dinner function, perhaps a snack for later?
The cummerbund makes up a formal tuxedo outfit and is included in the rental package. It should be worn pleats facing up (too catch the breadcrumbs) with a single breasted jacket, bowtie and no vest.
I would suggest sticking to a vest. If you must, stick to black, grey or as crazy as red, based on the theme with a matching bowtie.