If i had to guess, it could be a lightweight yet super sturdy carbon-fiber composite machine. You could cut the weight of a longarm sewing head by 50% or more.
My next guess, make something like a Roomba (robotic vacuum cleaner, lol) but it is a sewing machine. The undercarriage would connect to the top by magnets.
Third guess: take a special pen and draw lines. Machine magically sews over them and erasesmthe markings.