Had some soft styrofoam laying around.
Just measured all the areas in and around the opening and cut out to fit tight.
You'll see what to cut when you take the armrest out.It's kinda like routing out part of the bottom.
Then pulled the fabric tight and I just pushed in some finish nails to hold it.
My daughter has popped it out with her feet when she comes across to the front seat,but just pick it up and push it back in.
Mine is mostly work car and then the kids are in back so it's ok this way for now.
One day I'll get a armless console,but I won't hold my breath.
rich