I have a portable table that I use for freemotion quilting by setting it next to my larger table so the quilt is supported on the back the table. I also have a small extension table that goes with the portable table and sits to the right. Both can be folded up and put away easily. It might be easier to put a portable table (like a card table) behind your desk rather than go to all the work to add an extension especially if you don't have tools to do that.