I just found out a problem my machine has-won't sit flat. It's held up on hinges and a little ledge. From what I was told, there is no insert for this.
It was suggested:
a. get a table or desk and cut it or have one made personally.
b. buy a new machine to fits with inserts: he suggested Janome Threadbanger TB12 (reviews are very good) for $199....
My machine is fine, nothing fancy at all. Better look for that old desk or table!