This piece is designed to block out the IO and allow for a 12mm Momentary Anti-Vandal Switch on the NR200. Photos show the process, but basically you remove the button, USB board & the sound board, then you need to snip the plastic under the button (permanent modification!). You place the print on the top, then push the button through the hole and tighten with the nut that comes with the button. This nut keeps the print in place. I had created versions where the print goes through the USB holes, but it ultimately ended up being far harder to print and not worth the effort.

I purchased my button on Aliexpress, but you can buy 12mm Momentary Anti-Vandal Switches in all manner of places.

You will need to print with a reasonable fine layer height given the taper. Or maybe try ironing?