I have a PC set up with 3 optical drives (to rip compact discs). One of the drives was salvaged from a pre-built machine that had a cover to hide the optical drive. As a result of this, the plastic piece (I would call it a bezel) on the tray has been removed.
See this image (third drive down) for clarification.
I have tried to find a replacement using terms such as tray cover, tray bezel, etc. on eBay and Aliexpress and I have turned up nothing. I am surprised that no replacement is available, as the three drives I have all share the same fitting for this part – it seems to be generic.
Here are two more pictures of the part I am talking about – it's hard to describe!