there's a lot of good ideas here. I have an HQ16 that I haven't had much time to use yet.
I purchased inexpensive white flat sheets, sandwich them with batting and practice. When I'm finished I serge the edges and use for mattress pad.
I haven't used the zippers yet, but I do want to.
I have the HQ set-up and I have a Brother PQ 1500S and a New Joy frame that I want to sell. PM me if you know anyone that is interested.
Good luck ladies and have fun