We spotted this bedframe on My Modern Met and it's for sale in Columbia, which might be a bit of a stretch for pre-Christmas delivery, before you even think of the travel miles but it is an easy diy - to make yourself or have someone handy put together.
If you have space under a bed and you are even slightly handy, with a couple of tools, this is super simple to make. And it doesn't have to be purrfect, because no one can see it. (You might want to make sure the walls are securely fastened together so things don't end badly for the cat.)
The makers are a company called Catlife and they believe the bedframe is the perfect solution for both owners and their 'clients'.
“UNDER THIS BED, THEY FIND A QUIET PLACE, FULL OF CALM AND SECURITY, AND BEST OF ALL, IT STILL HAS THE SAME FUNCTIONALITY FOR THE OWNER! YOU WILL CONTINUE TO REST AS YOU NORMALLY WOULD, BUT NOW, YOU PROVIDE A UNIQUE DEN TO YOUR CAT.”