I built my own sewing table, a 4x4 sheet of plywood. The sewing machine I cut an square hole for, then using 4 bolts made a shelf that I adjust for the perfect height to let the removable top of my Bernina 830 (old) sit flush on the top of the plywood. No issues with quilts sliding off as most of the room is on the left side of the machine. If I need to use the free arm (what free arm? I paid a lot of money for it) I lift the machine out of the hole and place it on top. Wait, never happens. I don't sew anything but quilts. If I need to put my back up Elna in there (Even Berninas need a tune up occasionally) I adjust the height of the shelf and ignore the space between the free arm and the side of the hole.
Works really nice. I did use to have a Pfaff I used on top of a desk all the time (in Europe) and found it to be a pain to sew on for more than a few hours at a time. tim in san jose