I can't think of something you could buy readymade. However, you might not be very crafty but I'd bet you could cut a hole.

From Walmart or a hardware store you should be able to find a medium/large Tupperware or Sterlite plastic storage container. There are colored and opaque ones since I'd assume you wouldn't want clear.

The cheaper plastic ones would likely be easier to cut so maybe also consider checking dollar stores if no luck at Walmart.

Wear some good gloves and with a decent heavy duty box cutter, you can make the hole whatever size you'd need. Careful not to leave the cut edges if the hole all jagged and sharp so people don't get scratched. A piece of sandpaper or even a nail file can clean up the edges.